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Young sunflowers track the sun across the sky, reaching new heights with every passing day - except, sometimes they don’t. Sometimes, a small injury can become infected and a black rot spreads around the base of the flower, finally engulfing it in a black goo that dries and hardens into a smelly shadow of what might have been. What causes this, and can it be prevented?  Bacterial head rot on sunflower (NDSU) Head rot, also known as pin rot, is a disease of sunflowers, lettuce, and broccoli, caused by the Pectobacterium carotovorum, subsp. carotovorum and P. atrosepticum bacteria. Symptoms of bacterial head rot The first symptom of bacterial head rot is nothing more than a small, brown, greasy or water soaked looking area on the surface of a cluster of unopened flowers or leaves. These lesions are usually seen at the sight of mechanical injury caused by bird and insect feeding, hail, or falling twigs. Bacteria enter the damaged tissue and that’s where the infection begins.  Bacterial head rot lesions (NDSU) Affected areas turn from brown to black as the infection spreads into surrounding plant tissue. There is a distinctly bad smell, similar to rotten potatoes, but it is rare for secondary fungal growths to occur when head rot is present. If the bad smell is absent and other bacterial and fungal infections are present, the infection is more likely to be caused by Alternaria fungi.  Bacterial head rot spreads into sunflower stem (NDSU) Bacterial head rot prevention and control
Cool winter and spring temperatures combined with prolonged periods of rain, fog, and dew provide the perfect medium for bacterial head rot pathogens. This means good air circulation between plants can go a long way toward preventing this disease. That’s a good thing, because chemical sprays and other treatments have not been consistently effective in preventing bacterial head rot. The best way to prevent this problem in your garden is to start with resistant cultivars, such as broccoli with dome-shaped heads, space plants properly, and avoid overhead watering.
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Whether you call them June beetles, Junebugs, or May beetles, these small, reddish-brown, clumsy flyers can be annoying. They get their name because of when they emerge. In the Bay Area, these pests come out in June. Other places get them in May, hence the difference.  Junebug (Missouri Extension)
Junebug damage Adult Junebugs feed on leaves. They fly in from weedy areas to feed at night. During the day, they tend to hunker down in a shady spot or burrow into the soil until dusk. The damage they cause is similar to Fuller rose beetles, earwigs, and snails. Grasshoppers and caterpillars may also cause similar damage. The only way to be sure is to catch them in the act. The more insidious damage occurs underground as Junebug grubs feed on the roots of your lawn, especially ryegrass and bluegrass. Symptoms of infestation include brown, dying patches. If things get really bad, you can actually roll up patches of turf because it is no longer attached to the ground! Large numbers of Junebugs can defoliate a young tree in a matter of days. This is especially true for avocado trees, which may need to be protected with netting.  Lawn damage by grub feeding (University of Nebraska) Controlling Junebugs
Commercial growers use blacklight traps when Junebug infestations cause too much damage. This is not recommended for home growers because the trap may attract more Junebugs than it captures. Heavy infestations are treated with an application of entomopathogenic nematodes. For the most part, home gardeners can’t do anything besides hand pick them whenever they are seen. Junebugs really are clumsy flyers, so it’s not hard to catch them. They are attracted to lights at night and often bump into windows and screens. When I catch them, I feed them to my chickens, who are very happy to help with Junebug control. If you have children, you can always gift them a butterfly net and offer a bounty on every Junebug they catch! Lack of vigor or sudden death by the phytophthora root and crown rot is nearly always caused by too much water. The name is from the Greek phytón (plant) and phthorá (destruction), so the name Phytophthora means the plant-destroyer. There are different types of Phytophthora that attack different host plants. What is Phytophthora root and crown rot? Phytophthora [fie-TOF-ther-uh ] is a family of water molds, called oomycetes. Oomycetes fall somewhere between fungi and algae in the web of life. There are many different types of Phytophthora molds. They generally attack stems and roots. Stem damage normally occurs at or just above the crown, where the stem meets the roots, at the soil line, though it can also occur elsewhere on a plant. These molds cause many different plant diseases, including sudden oak death, potato blight, damping-off disease, and crown rot. Phytophthora root and crown rot, in particular, can kill a tree or shrub if the soil remains wet for too long, or when planted too deeply. [Moist soil around the trunk is never a good idea.]  Darkened bark and wood tissue is a symptom of Phytophthora crown and root rot (UCANR) Host plants Nearly all fruit and nut trees, including cherries and kiwifruit, are susceptible to Phytophthora root and crown rot. But so are alfalfa, and members of the nightshade and cabbage families. This means tomatoes, eggplant, and potatoes are vulnerable, as are kale, cauliflower, Brussels sprouts, broccoli, kohlrabi, horseradish, cabbage, collards, turnips, rutabagas, radishes, bok choy, and mustard. And all because of too much water. Symptoms of Phytophthora root and crown rot Plants affected by Phytophthora root and crown rot look drought stressed. This is particularly unfortunate because the natural response is to provide more water - the last thing you want to do when Phytophthora is present. Symptoms normally start in just one branch or area of the tree or shrub before spreading to the rest of the plant. Leaves may turn purple or reddish. Sudden wilting and plant death may occur when the basal stem or crown are attacked, or the mold may attack the root system, causing plants to linger poorly for years before dying.  Brussels sprouts plant infected with phytophthora shows reddish colder leaves (UCANR) Symptoms can vary greatly, depending on the type and age of plant, the plant’s genetic resistance to infection and overall health, as well as soil temperatures and moisture levels, but you will probably see darkened areas of the bark around the crown and upper roots of infected plants. You may also see dark sap or gum oozing from damaged areas. Using a sharp knife, you can cut away an area of bark. Infected trees will show reddish brown streaks or patches. Water-soaked areas on roots may also be visible. If you also see white threads between the bark and the inner layer, or around the roots, the infection is from Armillaria root rot, rather than Phytophthora.  Reddish brown patches visible under the bark infected with phytophthora root and crown rot (UCANR) Preventing Phytophthora root and crown rot infestation Proper water management is the best way to prevent and control Phytophthora root and crown rot. Never allow standing water to remain around tree and shrub trunks. Also, don’t let sprinklers hit tree trunks. These other tips can help you manage Phytophthora in your garden or landscape:
You may be able to maintain an infected plant, with proper irrigation and good cultural practices, but it will never be the same. Phytophthora can stay in the soil for many years, so prevention is far easier than control. NOTE: One new-to-us variety, Phytophthora tentaculata, is on the Dept. of Agriculture’s watch list. If it appears in your garden or landscape, please contact your local Cooperative Extension Office right away. They may have helpful advice that will protect your plants, and they need to know how far this disease is spreading.
If older leaves on cucumber, melon, or squash are turning yellow and leathery, the plants may be infected with cucurbit aphid-borne yellows. This viral disease is transmitted by the cucurbit aphid-borne yellows luteovirus (CABYV). Luteoviruses are a genus of viruses that use plants as hosts, and are transmitted by aphids.  Aphid borne yellow virus (UCARN) Symptoms of aphid borne yellow virus
Early symptoms are chlorotic (yellow) areas on lower leaves. These spots expand to include the entire leaf, leaving the larger veins bright green. The affected areas become leathery and brittle. Stunting and fruit drop are common as the plant struggles. Before genetic testing, this condition was attributed to plant aging (senescence), nutrient deficiencies, or other diseases, such as cucurbit yellow stunting disorder. How the disease is spread As the name suggests, this disease is spread by aphids. As aphids pierce plant tissue to feed on sap in the xylem, they infect the plants they eat. Once infected, the aphid will continue to spread the disease as it feeds. This disease can also be spread to lettuces, beets, and several weeds. Controlling cucurbit aphid borne yellows There is no way to control the virus, but you can reduce the presence of aphids in your garden with these tips:
Infected plants should be removed and destroyed, to prevent the disease from spreading to nearby plants. Crawlers with no legs, a species with no males, and broody females who keep thousands of eggs warm and safe - what are these garden pests? Citricola scale. Native to Japan and southern China, citricola scale is currently found in California, Arizona, and Maryland, and in several other countries. Also known as grey citrus scale, citricola scale (Coccus pseudomagnoliarum) can be found feeding on citrus and pomegranate twigs in spring and early summer, and immature scale insects can be found feeding on the underside of leaves in late summer and fall. In addition to feeding on pomegranate, lemon, lime, orange, and grapefruit, these sap-sucking pests also feed on elm, bay laurel, hackberry, and oleander.  Adult citricola scale (UGA) Citricola scale lifecycle There are only female citricola scale insects. They reproduce asexually (parthenogenesis). Each female can produce between 1,000 and 5,000 eggs during the summer. She will keep her eggs safe under her body until they hatch out in to crawlers, usually from June through August. That may sound like a crazy broody season, but citricola scale eggs hatch after only 2 or 3 days. The babies that come out of those eggs are called crawlers. The name crawlers sounds a little misleading because they don’t look as though they could do anything. But they do. These crawlers move to a good feeding site, attach themselves, becoming sessile (fixed), and feed until they molt into second instar nymphs, usually around November. These nymphs produce a lot of honeydew and are often protected and farmed by ants.  Citricola scale nymphs (UCANR) Citricola scale description Citricola scale start out as a yellow, oval egg. First instar crawlers are oval, flat, and nearly translucent. Sometimes they are yellowish-green to brown. Second instars are mottled brown. Citricola scale adults are one-quarter of an inch long, grey, oval, and flat. Well, slightly convex, but flat enough. They can be difficult to see because they start taking on the color of the twig to which they are attached. Citricola scale are often confused with brown soft scale.  Adult citricola scale (UGA) Citricola scale or brown soft scale? Citricola scale tends to have only one or two generations each year, while brown soft scale can have multiple generations going at any one time. This means that citricola scale insects you see will nearly always be at the same life stage, while brown soft scale specimens may be at any life stage. Also, adult citricola insects are grey, while brown soft scale adults are brown or yellow.  Brown soft scale (Whitney Cranshaw) Damage caused by citricola scale
Underneath those tiny domes of protection, citricola scale attach themselves to stems and leaves of citrus and pomegranate. They pierce the surface to reach the phloem, to siphon away valuable nutrients and sugary sap, weakening the tree. And they poop. This poop, called honeydew, contains a lot of sugar, and it creates the perfect growing medium for sooty mold fungus. Sooty mold blocks photosynthesis, further reducing your tree’s vigor. Citricola scale can reduce flowering and fruit production. During heavy infestations, twigs can be killed by citricola scale. How to control citricola scale Regularly monitoring citrus and pomegranate trees for these pests is your first line of defense. If you notice ant trails or sooty mold, take a closer look at twigs and leaves for signs of scale. Since ants protect these pests, you can eliminate that protection, making the citricola scale more vulnerable, by wrapping the tree’s trunk with a sticky barrier. Also, there are naturally occurring parasitic wasps that will control citricola scale insects (as long as you do not apply broad spectrum pesticides). Applying dormant oil in winter can also help reduce citricola scale populations. Research has shown that 40% of citricola scale in San Joaquin Valley are resistant to organophosphates. It is believed that there is also a cross-resistance to malathion and carbaryl. This looks to be yet another example of chemical pesticides actually making the pests stronger, as we add more poisons to the environment and our food chain. Bottom line, to control citricola scale on your pomegranate and citrus trees, inspect twigs very closely in April through June, and then look at the underside of leaves in late July. These pests can then be flicked off the leaf or stem with your fingernail. Relatively new to the United States, the European pepper moth is poised to cause significant damage to gardens and commercial agriculture. Each time an invasive plant or pest is brought into an area, there’s no telling what might happen. Resident predators or local diseases may make short work of the interloper. Then again, the insurgent may find a rich, predator-free environment perfectly suited to a population explosion. We don’t know, yet, which way things will go for the European pepper moth, but it’s probably a good idea to know what we’re up against, just in case.  Adult European pepper moths, showing cream-colored abdominal rings (purple arrows); males have a longer, slimmer abdomen compared to females (green arrows); and cream-colored wavy lines (pink arrows) across the middle of the hindwings. (James Hayden, UFL) Plants damaged by European pepper moths It’s difficult to get excited about something that hasn’t directly caused damage in your garden, so here’s the list of just some of the plants harmed by the pepper moth:
If that list doesn’t get your attention, I don’t know what will. Also on the list of favorite foods are roses, African daisies, azaleas, orchids, and many other flowers and ornamentals. Damage caused by pepper moths The moths themselves don’t cause any harm to plants. Like other moths and butterflies, it is the larval stage, or caterpillar, that feeds voraciously on leaves, roots, buds, fruit, and flowers. Pepper moth caterpillars may girdle young seedlings, causing what looks like damping off disease. Later larval instars may burrow into stems unnoticed, until the the stem collapses. Leaf damage starts out looking crescent-shaped, similar to damage by the Fuller rose beetle, or round, but the entire leaf ends up being eaten. Feeding is normally seen in the lower leaves, then moving up the plant until it is completed defoliated. Feeding on the roots can interfere with a plant’s overall health and vigor and feeding on buds, flowers, and fruit, well, there goes your crop. So, what does the European pepper moth look like? Pepper moth identification and lifecycle Also known as the European marsh pyralid, adult pepper moths (Duponchelia fovealis) have a wingspan of approximately three-quarters of an inch wide and a body less than half an inch long. The forewings are grayish-brown with two distinct yellowish-white transverse lines. The outermost line has a “finger” that points backwards.  Adult European pepper moth, showing yellowish-white transverse lines (red arrows) and "finger" (yellow arrow). (Carmelo Peter Bonsignore, UFL) At rest, the pepper moth holds its wings out to either side in a triangular shape. The head, body, and antennae are olive brown, and the abdomen features cream-colored rings. Legs are pale brown. Both sexes have long abdomens, but the male’s is unusually long, and he holds his curved upwards at rest.  Male European pepper moth showing up curved abdomen at rest (Carmelo Peter Bonsignore, UFL) Pepper moth eggs are really tiny (1/50 of an inch). The eggs start out whitish green or pale yellow, which turn pink, then red, as they mature. Just before hatching, the egg turns brown. Eggs are laid singly or in batches on the underside of leaves, normally near the leaf veins. Eggs can also be found on stems, at the crown, in the soil, on the tops of leaves, and even on greenhouse walls and furnishings.
Caterpillars start out salmon pink with a black head, and a line of grey and brown spots along each side. Some sections may feature a double row of dots. Using a hand lens, you can see a hair emerging from each spot. Just behind the head, you can also see a hard plate, which is the same color as the head. As they grow, the pink turns a dirty white color that can range from pure white to pale or even dark brown, depending on which of your garden plants they are eating.  European pepper moth larva (Lyle Buss, UFL) These caterpillars can grow to over an inch long. Just before pupating, they may lose their spots. Pepper moth caterpillars create a cocoon out of soil, frass, and webbing. The cocoon can be 1/2 to 3/4 of an inch long.  Cocoon and pupa of European pepper moth (James Hayden, FDACS) A single female pepper moth can lay up to 200 eggs. Under optimal conditions (temperatures around 68°F), those eggs can hatch in 4 to 9 days. Over the next 3 or 4 weeks, the caterpillars feed ravenously. Then, pupation takes 1 or 2 weeks. Adult moths live to mate and procreate for a week or two and the whole process beings again. In greenhouse environments, 8 or 9 generations a year can occur. That ends up being a lot of pepper moths! In areas like California, where cold winters rarely occur, this pest could prove to be devastating. These moths have an unusual flight pattern - both males and females fly fast and low, with their abdomens curved upwards. You may see individual moths, or they may swarm. Pepper moth caterpillars are photophobic, which means they do not like light. If you shine a flashlight on a pepper moth caterpillar, it will become agitated, moving rapidly side to side. How the pepper moth got here Pepper moths have been present in Europe for a very long time. In 1984, it became a greenhouse pest in Europe and Canada for the cut flower, vegetable, and aquatic plant industries. It is believed to have been spread globally through infested plants from those products. [Yet another example of why it is so important to quarantine new plants!] By 1988, the pepper moth had developed a taste for strawberries. In 2004, the pepper moth was found on begonia plants in San Diego, CA. It was again detected in 2010. By 2011, the European pepper moth had been found in seventeen California counties, as well as in fourteen other states. Departments of Agriculture in each of these states is monitoring for this pest. If you think you see one, please try to capture it and report it to your local County Extension Office. Native to Europe, the pepper moth moth prefers fresh and saltwater marshes. You might think, since you don’t have a marsh in your garden, that your plants are safe. But most of us have a creek, reservoir, or some other body of water nearby, and a pepper moth can fly up to 62 miles.
Also, check the debris (detritus) that falls from container plants and around the base of the containers for signs of eggs or pupae. You can also lightly brush the soil around potentially infested plants for signs of pupae and cocoons.
How to control European pepper moths At this point, the best biological controls are to spray Bacillus thuringiensis (Bt) or beneficial nematodes (Heterorhabditis bacteriophora and Steinernema spp.). Rove beetles seem to enjoy feeding on pepper moth eggs and caterpillars, and certain predatory mites and wasps also parasitize these pests, so avoid using broad-spectrum pesticides. Since pepper moths prefer moist, hidden areas, keeping your garden tidy and free of overly moist areas can reduce the chance of perpetuating the species in your neck of the woods. Again, because this is a relatively new pest, with the potential for significant long term damage, if you see one, please report it. If you live in California, you can call 1-800-491-1899. If you live elsewhere, contact your local Department of Agriculture for reporting instructions. Knowing where this pest is can help in its eradication, which is really good news for your tomatoes, basil, figs, and cucumbers! What's eating your trees? If you see orange frass and bark damage, it's probably the American plum borer.  American plum borer larvae borne in scaffold crotches of young trees (UCANR) Like flathead borers, clearwing moths, and shothole borers, the American plum borer (Euzophera semifuneralis) feeds on the cambium layer of branch crotches, the lower trunk, and the root crown. This feeding weakens and damages branches, and can even kill a young tree. Host trees American plum borers feed on many popular fruit and nut trees, as well as several ornamentals. Here is a partial list of trees favored by plum borers: Plum borer lifecycle Each spring, adult plum borers emerge, mate, and eggs are laid in bark wounds. These wounds can be caused by branches rubbing together, a poorly aimed weedwacker, a careless pruning job, or any number of other insect pests. Also, branches that are growing too close together or at a tight angle, and heavily furrowed bark, can provide the necessary shelter. When the eggs hatch, larva enter the bark wound and begin feeding on the cambium, which contains the vascular tissue carrying water and nutrients throughout the plant. The larvae burrow shallow, irregularly-shaped tunnels between the wood and the bark. These larvae go though several stages, or instars, growing progressively larger, over the next 30 to 38 days. Finally, the larvae pupate in a loosely spun cocoon, inside the tree, where they overwinter. There can be up to four generations each year. Pupae that occur during the early part of the season can reach adulthood in as little as 10 days.  Adult American plum borer (xpda) Plum borer description Adult plum borer moths are dark grey with black and brown wing markings. The legs and body of the adult moth are a dusky grey with a reflective bronze. The wings have a white fringe. The larva can be white, green, or pink and are usually one inch long. If you use a hand lens, you should be able to see a circle of tiny hooks on the bottom of a plum borer’s fourth set of feet (B), called prolegs, as opposed to clearwing moth larvae (A), which have two rows of hooks. [Now you know how larva can climb up vertical surfaces!] More often, you will see the damage caused by the American plum borer, long before you actually see the insect.
Damage caused by plum borers
As plum borers feed, they leave behind a trail of destruction. Reddish orange frass collects wherever they feed. Also webbing and extensive gumming can be seen. Gumming is a gooey discharge plants use to protect themselves. The gum hardens as it dries, but, unlike sap, it is relatively easy to wash off. Eventually, branches are weakened to the point of breaking and the tree’s overall health declines, reducing or eliminating any chance of harvesting those delicious plums. Controlling plum borers Plum borers are easier to prevent than control. Once they enter a tree, they are relatively safe from predators and pesticides. Use these tips to prevent a plum borer infestation:
If a bark injury is already present, or if your tree has bacterial galls or a fungal canker, and you know that plum borers are nearby, it may be worthwhile to hire a professional to apply a residual, contact insecticide. Over-the-counter products are not effective against the American plum borer. Yesterday, I harvested the very first, sun-warmed, tangy-sweet raspberry of the season. To me, raspberries rank right up there with tomatoes for good reasons to grow your own. Store bought raspberries rarely have the flavor or plump texture that fresh, homegrown raspberries provide. That being said, cane blight can take all the fun out of growing raspberries at home. If you know what to look for, you can prevent this disease from spreading.  Raspberries (Fir0002) Cane blight is a fungal disease. The fungus responsible for cane blight goes by the name Leptosphaeria coniothyrium. It is also known as Paraconiothyrium fuckelii. [Apparently, someone hates this disease even more than I do!] Cane blight is most commonly seen on raspberries, but it can also attack blackberries. The same fungus also causes a rose canker and a root rot on strawberries. Other host plants include bamboo, juniper, stone fruits, blueberries, and currants.  Cane blight symptoms on blackberry (UCANR) Symptoms of cane blight This disease starts out looking similar to fireblight, spur blight, and anthracnose, but it progresses differently. Canes infected with Leptosphaeria coniothyrium will develop purplish-black lesions at wound sites. These lesions will develop into black or brown cankers that encircle the cane, causing wilt and twig dieback. Infected canes may also twist around other stems, rather than growing normally. Bark may split and the wood becomes very brittle. Leaves and fruit on those canes will wither and die, but stay attached to the cane. If you look closely, you can actually see tiny, black fungal bodies on the wood. Preventing cane blight Fungal spores can blow in on the wind and be splashed up onto plants by rain, sprinklers, and overhead watering. Spores enter healthy canes through injury sites. Jagged pruning cuts, growth cracks, and damaged roots can all provide points of entry, so keeping plants healthy and protected is the best way to prevent this disease. Use these tips to help prevent cane blight on your raspberries:
 Unripe raspberries growing on healthy canes (Kate Russell) How to control cane blight
The only control is removal of infected canes. The cane blight fungus overwinters on the canes, so infected canes should be removed and destroyed. Be sure to dip your pruners in a solution of one part bleach and nine parts water, or bathroom disinfectant can be used. Severely infected plants should be removed completely. Fungicides are not effective against cane blight. Keep your raspberry plants healthy for many years of summer deliciousness! If you see yellow spots that spread to fill the spaces between leaf veins, your melon or squash plants may have cucurbit yellow stunting disorder. Cucurbit yellow stunting disorder (CYSD or CTSDV) is a viral disease of cucurbits, carried by whiteflies. Cucurbits are popular garden plants. They include summer squash, winter squash, watermelon, muskmelons, pumpkins, cucumbers, and more. Since some whitefly species can travel relatively long distances, this disease can find your garden throughout the growing season. To reduce the chances of the infection spreading from one plant to another, it is a good idea to learn how to recognize this disease in its earliest stages.  Cucurbit Yellow Stunting Disorder (UCANR) CYSD Symptoms The first symptoms of CYSD look a lot like water stress, as the virus begins spreading throughout the plant. Then, yellow spotting on older leaves will develop. This yellow spotting can also mean the plant has a molybdenum deficiency, or that it has cucurbit aphid borne yellow virus (CABYV). You can take a leaf sample to your nearest county farm advisor, where they will conduct a molecular test to verify the disease.  Molybdenum deficiency on melon foliage (UCANR) If the chlorotic areas spread to the point that the entire leaf is yellow, except for the veins, it is likely to be CYSD. Small green patches may appear in the yellow areas. Other symptoms include leaves curling upwards and becoming brittle. As the disease progresses and the vascular system breaks down, older leaves are dropped and fruit is neglected, as the plant tries to protect itself. This makes fruits smaller, less flavorful, and more prone to pests and other diseases. Also, fruits from infected plants do not store as well as fruits from healthy plants.
Controlling CYSD There are no effective chemical or biological controls. Since CYSD is spread by whiteflies, whitefly control is key to halting the spread of this viral disease. These tips can help reduce the chances of CYSD spreading through your garden:
Protect your cucurbits from whiteflies for an abundant harvest this summer and fall! Who wants scabby apples? Yuck! If you see pale yellow spots on your apple leaves, fruit, and stems, that turn brown, your tree may be infected with apple scab.  Apples infected with the apple scab fungus (UCANR) Apple scab is a fungal disease that can defoliate your tree and destroy your crop. This disease is most common in areas with cool, moist weather in spring and early summer. This disease can also affect ornamental crabapple. Before losing your apples to the Venturia inaequalis fungus, let’s see what we’re up against. Apple scab symptoms Apple scab starts out as chlorotic (yellow) spots on leaves. Then dark, olive-colored spots appear on leaves and fruit. In severe cases, these spots may also show up on stems. If you look on the underside of infected leaves, the surface will look velvety. That ‘velvet’ is fungal growth. Affected leaves may also pucker or twist. Severe infestations cause leaves to turn yellow and fall from the tree. Infected stems can lead to blossom drop. Finally, later in the growing season, sooty or greasy grayish-black areas appear on the fruit. These lesions often have a red halo. As the fungi develop, the area becomes sunken, tan colored, and scabby. The fruit may also become distorted and crack, providing other pests and diseases with a point of entry.
Apple scab lifecycle When infected leaves fall from the tree, they take fungal spores with them. These spores then overwinter on these leaves. When rain or sprinkler water hits these leaves, the spores can be bounced back into your tree, where they will germinate and start the whole process over again.  Apple scab lifecycle (UCANR)
For the backyard orchardist, the easiest way to break the apple scab disease triangle is to remove and dispose of infected leaves. [This disease can also overwinter on nectarine and peach leaves.] Commercial apple growers may apply zinc and fertilizer-grade urea to leaves in autumn to speed leaf drop, and apply fungicides during the rainy season, at budbreak and a month after petal fall. but these are probably not practices you want to be doing at home. If your apple tree(s) become severely infected, you can use fixed copper, Bordeaux mixture, sulfur, or neem oil can be used from the time green tips appear, until the tree is in full bloom. Avoid using these treatments after that time as they can cause fruit russetting. And be sure to follow the directions for any of these treatments carefully. For example, applying sulfur within 3 weeks of using horticultural oils, or on days when temperatures are above 90°F can lead to phytotoxicity.
As you conduct a weekly inspection of your apple tree each spring, be sure to enjoy the emerging blossoms! If you see tiny dark nubs on your citrus or olive twigs, your tree may be infested with black scale. Black scale (Saissetia oleae) build a soft, thin, way covering over themselves as protection. Unlike armored scale insects, this protective covering cannot be removed from soft scale insects. Black scale is a type of soft scale that produces a lot of honeydew. Honeydew is a nice way of saying sugary bug poop. Honeydew provides the perfect growing medium for sooty mold. It also attracts ants, which can carry diseases.  Adult and immature black scale (UCANR) Black scale damage
All scale insects are sap-suckers. They use piercing mouthparts to access vascular tissue within the host plant. This feeding weakens the host plant, leading to fruit drop, wilting, twig dieback, stunting, and overall loss of vigor. In this weakened state, citrus trees are more susceptible to damage by drought, temperature extremes, other insects, and disease. Heavy infestations of black scale can kill part or all of a tree. Black scale lifecycle Each May and June, here in California, and again in October and November, female black scale insects lay as many as 2,000 eggs, without ever mating! These eggs hatch out into crawlers, which crawl around on the host plant, looking for a nice place to set up shop, usually on leaves. These crawlers go through several instars, or stages. In the second instar, they develop a ridge on their back. This ridge expands into an “H” shape. After they molt a second, time, they head for twigs, and begin growing in earnest. This is where their bodies become more circular and their protective cover turns a leathery mottled gray. As each of these offspring approaches reproductive age, the cover gets darker and harder, and the “H” often disappears. How to control black scale Black scale insects tend to be a serious problem every 5 to 10 years. Normally, local parasitic wasps and other predators keep this pest under control. Dust and the use of broad spectrum pesticides can interfere with these natural controls. In years of heavy infestation, specific pesticides may be needed. Before using a pesticide against scale insects, be sure to look closely. If you see tiny holes in the scales, there is no need to spray. Those holes are from scale parasites which have already done their job. You can also reduce scale populations by hand. Simply grab a wet, soapy rag and start wiping them off. While you’re at it, you can help your tree increase photosynthesis by wiping off the sooty mold, too. This pest is an outlaw, of sorts, carrying death and disease in its wake. Glassy-winged sharpshooters may have a cool name (and they look pretty amazing), but they are a serious pest that carries several diseases to your garden and landscape plants. This pest first appeared in the Bay Area in 2001 and efforts are being made to control its spread. Let's see how we can help control this pest.  Adult glassy-winged sharpshooter (UCANR) Glassy-winged sharpshooter description Sharpshooters are a type of leafhopper. They have narrow bodies and strong legs. Glassy-winged sharpshooters tend to be 1/2 inch long and dark, shiny brown above, and yellow underneath. The wings are clear with reddish veins and spines can be seen on the hind legs, if you look closely.  Glassy-winged sharpshooter nymph (UCARN) Glassy-winged sharpshooter lifecycle Clusters of white eggs are laid on the underside of leaves and then covered with a white, powdery coating, called a brochosome. This coating and the nearby leaf tissue turn brown after the eggs hatch and the nymphs use their piercing mouth parts to suck sugary sap from the xylem. These nymphs will molt several times before reaching adulthood. While sharpshooter feeding is not a serious threat to healthy host plants, these insects carry many diseases, and their excrement forms a coating on leaves that looks like whitewash and falls on cars below. Heavy feeding on new, small plants can cause wilting. Sharpshooter host plants These pests are opportunists. Scientists estimate that there are over 700 different types of plants used by sharpshooters as food. These plants include grapes, citrus trees, and stone fruits. This means most of the fruit and nut trees in your garden or landscape are susceptible to these pests. What’s worse, as these pests feed, the bacteria they carry is injected into the plants! Diseases carried by glassy-winged sharpshooters The glassy-winged sharpshooter (Homalodisca vitripennis [formerly H. coagulata]), like other sharpshooters, are sap-sucking insects. As they feed on plants infected with the Xylella fastidiosa bacteria, the bacteria begin reproducing within the insects mouthparts. When the sharpshooter feeds on successive plants, the bacteria and the diseases they cause, are also transferred. These pests can bring several, currently incurable, diseases to foodscape, including:
*These diseases have not yet been found in California, as of April 2018.  Adult glassy-winged sharpshooter (Santa Clara County) How to control glassy-winged sharpshooters
Insect predators, such as parasitic wasps, and naturally occurring pathogens are the most effective, long-term control measure, so avoid using broad-spectrum insecticides. In severe cases, insecticides may need to be used. Just be sure to use them sparingly and follow the directions exactly. Insecticidal soaps and oils have also proven effective. If you see a glassy-winged sharpshooter, please contact your local Sheriff or County Extension Office right away! [Yes, I’m kidding about the Sheriff. But I’m serious about the County Extension.] Almond trees are lovely in a landscape and they can produce up to 65 pounds of almonds a year. As far as fruit and nut trees go, almonds have shown themselves to this gardener to be trouble free, but problems can happen. One of those problems is called almond leaf scorch.  Marginal leaf scorching (UCANR) Almond leaf scorch is caused by the same bacteria (Xylella fastidiosa) that causes Pierce’s disease in grape vines, and alfalfa dwarf disease. This disease can also infect many common weeds, including annual bluegrass, burclover, cheeseweed, chickweed, filaree, London rocket, and shepherd’s purse. This pathogen is found on many familiar plants, such as bermudagrass, blackberries, elderberries, fescue grasses, nettle, and rye, without causing any problems for the host plants. How almond leaf scorch spreads This disease is carried by sap-sucking insects, such as leafhoppers, sharpshooters, and spittlebugs. As they feed, the bacteria moves from the insect into the plant’s xylem, where it begins to reproduce.  Healthy almond tree (Kate Russell) Almond leaves are normally a lovely green color. Around June, however, you may notice the edges (margins) of leaves look scorched. If you look closely, you will see a yellow band between the scorched portion and healthy leaf tissue. This scorched appearance looks a lot like salt burn, but salt burn lacks the yellow band. This disease is normally seen on one branch, or one scaffold of branches. {Scaffolds are major horizontal branches.] Over time, this disease spreads to the rest of the tree. Another name for almond leaf scorch is golden death. While infected tres can live for several years, they will leaf out later and be far less productive than a healthy tree  Zonate pattern (multiple area) scorching (UCANR) Leaf scorch management
If your beloved almond tree becomes infected, early detection is critical. The infected branch, or its scaffold, should be removed 5 to 10 FEET below any visible symptoms. Keep a close watch to see if any signs of infection appear elsewhere on the tree. If the tree is less than 10 years old, your best bet is simply to replace the tree. I hope that your almond tree never faces this problem, but now you know what to watch for. The tiny Asian citrus psyllid is costing orange growers billions of dollars in losses, and it might be on your trees!  Asian citrus psyllids (CDFA) The Asian citrus psyllid (Diaphorina citri) arrived in North America from Asia or India in 1998. The insect feeds on the sap found in leaves and stems of citrus trees. As they feed, they produce large amounts of honeydew (sugary bug poop). This honeydew is a popular food of ants and the sooty mold fungus. That wouldn’t be a serious problem, by itself. The situation is made far worse because the Asian citrus psyllid carries a bacteria that causes a devastating disease called huanglongbing (HLB). Also known as citrus greening, HLB is a vascular disease that kills trees and there is no cure. Trees infected with citrus greening must be destroyed.  Asian citrus psyllid (CDFA) Asian citrus psyllid identification This pest is about the size of a grain of rice. It is a mottled brown color with a light brown head. The wings have a dark brown band around the outer edge and look as though they are being held up and behind the insect when at rest. Most adults have a dusty appearance. Nymphs are yellowish orange with long, white waxy secretions, called tubules. Tiny, almond-shaped eggs start out pale, turn yellow, and then orange just before hatching.
Asian citrus psyllid lifecycle Adult females lay between 300 and 800 eggs. These eggs are laid on new growth, on shoot tips and between unfurling leaves. Nymphs go through five instars. The entire lifecycle takes from 15 to 47 days, depending on conditions. There can be up to 10 generations a year. [I don’t know about you, but that’s some crazy math. If there are any mathematicians reading this post, I would love to read in the comments just how many offspring that can mean!] Host plants and signs of infestation You can tell by the name that these pests feed on oranges, lemons, limes, and grapefruit. They have also been found feeding on kumquat (Fortunella sp.), Indian wood apple (Limonia polyandra), jasmine, citron (Citrus medica), pummelo (Citrus x maxima), mock orange, Cape chestnut, Bengal quince (Aegle marmelos), and others. There are several signs of infestation that all citrus tree owners should watch for on a frequent basis:
Financial impact of Asian citrus psyllids Some pests are more costly than others. This one tops the list. Infection of citrus trees around the world is wiping out entire regions of citrus growers. Companies that sell citrus products are paying more for domestic citrus, and they must also buy citrus products from other countries, causing the loss of local jobs. Also, over $1 million a year is being spent on public education, to slow the spread of this problem. This means even higher prices. The reason for this educational investment is that there are more citrus trees in backyards than in commercial orchards. Uninformed homeowners are far more likely to allow this pest to expand its range even further. Halting the spread of citrus greening Learning what to look for is one of the best ways to help slow this threat to citrus. These tips will go a long way toward preventing the spread of this disease:
Please read my post on huanglongbing disease and find out if you are in or near a quarantine zone. It is up to citrus tree growers everywhere to help combat this devastating pest. If you suspect or see signs of the Asian citrus psyllid or huanglongbing disease, immediately contact the CALIFORNIA DEPARTMENT OF FOOD AND AGRICULTURE HOTLINE: 1‐800‐491‐1899, or your local Department of Agriculture. Western tussock moth caterpillars can defoliate a tree in record time and they are wrecking havoc in Mountain View. There are over 2,500 species of tussock moth (Lymantriinae) worldwide. The family name Lymantriinae comes to us from the Latin word for ‘defiler’. Cousin to the gypsy moth of East Coast nightmares. the western tussock moth is making itself felt here, in the Bay Area.  Western tussock moth larva (UCANR) Western tussock moth caterpillars feed on leaves and young fruit. What makes these pests so much of a threat is how much and how fast they eat. Western tussock moth larva, or caterpillars, will feed heavily on apple, apricot, cherry, citrus, pistachio, plum, and prune trees, as well as many ornamentals, such as oak, ceanothus, and willow.  Large live oak tree defoliated by tussock moth caterpillars. Photograph by Lyle J. Buss, University of Florida. Western tussock moths (Orgyia vetusta, formally known as Hemerocampa vetusta) are normally present in this area, being native to the west coast of North America, but chilly winter weather and natural predators usually keep their numbers limited. Warmer winter weather allows these moths have a boom population, and 2018 is one of those years. Currently, local parks and walking trails are finding trees, sidewalks, and park equipment covered with these caterpillars. Caterpillars are falling out of trees onto cars and people, there are so many of them. Newly hatched caterpillars have a habit of using a silk thread to balloon themselves to a new location. Walking into a cloud of ballooning caterpillars isn’t something most people enjoy. Western tussock moth description These pests are easy to identify. A Western tussock moth caterpillar is 1-1/2 to 2 inches long and features white tufts (called pencils) that stick up along the back, with two black tufts on its head, and one on its read end. They also have paler tufts along their entire length and sides. You will also see bright red and orange spots. The adult female moth is unique in that she does not fly. She is short-winged (brachypterous) and stays with the cocoon. She is a pale grey color, but you probably won’t see her. The males find her because of chemical scents, called pheromones, that she releases. The male moth does have wings. He also has prominent, fringed antennae. He may be dark or light brown, depending on the local environment, with black and white markings. Larva go through several stages, called instars. Until they reach their full size, they are black, with black hair pencils on their first four abdominal segments.  Young western tussock moth caterpillars (NPS) Western tussock moth lifecycle Adult moths do not feed. Each female moth lays hundreds of eggsEggs are laid directly on the cocoon. The female moth covers the eggs with a protective coating and then covers that with a camouflaging layer of hairs (setae) from her own body. The eggs overwinter in this protected state and then hatch in May, June, and July, here, in the Bay Area. These caterpillars feed intensely for 40 to 60 days before pupating. While the caterpillars of some tussock moth species spread an irritant on the setae (hairs) that cover their bodies, the western tussock moth does not fall in that group, but they can be a pain, nonetheless.
Western tussock moth controls
Local governments use several methods to control heavy infestations of western tussock moth caterpillars:
Hopefully, your garden and landscape will be spared a visit from the western tussock moth. If you are not so lucky, you can spray Bacillus thuringiensis (Bt) to deter these pests. If a severe infestation does occur, you may have to prune out heavily affected limbs. Under the bark of your fruit trees, there may be tiny bark beetles, chewing destructive tunnels. There are over 200 different types of bark beetles in California (600 nationwide). We currently host 20 invasive species of bark beetle, half of which were only discovered since 2002. The shot hole (or shothole) borer has been here long enough that it is considered naturalized.  Shothole borer adult (E. Beers) Bark beetle galleries Bark beetles spend most of their lives in a system of tunnels, called a gallery. They chew these tunnels under the bark, in the sapwood or cambium layer. If you pull the bark away from an infested area, the gallery can clearly be seen. As the larvae feed on sapwood, expanding the gallery, these tunnels crisscross each other, damaging the xylem and phloem, making it difficult for trees to transport water and nutrients. Parent tunnels tend to be 2 inches long and run parallel to the grain. They are normally clean. Larval tunnels, like a teenage boy’s room, radiate away from the parent tunnels, against the grain, are smaller, and tend to be filled with frass and sawdust.  Shot hole borer gallery (MSU Extension) Shot hole borer host plants Shot hole borers, also called fruit tree bark beetles, prefer (you guessed it!) fruit trees, especially those in the stone fruit family. This means your almond, apricot, cherry, nectarine, and peach trees are susceptible, along with apple, pear, and avocado. Shot hole borers also feed on English laurel, mountain ash, hawthorn, and elm. Shot hole borer lifecycle and feeding Shot hole borers (Scolytus rugulosus) start out as white, round or oval eggs, laid in the gallery. These eggs hatch out into white, legless larvae that are 1/6 of an inch long and slightly larger just behind the head. These larvae overwinter in the gallery, creating more tunnels. As they feed, they poop. To make room for this material, the borers widen their tunnels and push the poop out, leaving signs of frass and sap to drip down the side of your tree. All this chewing causes further damage to the tree’s vascular bundles.  Shothole borer larval galleries in wood (H. Riedl) After 6 to 8 weeks of tunneling and pooping in your fruit tree, the larvae are ready to enter a pupal stage. Pupae are white, with tiny hairs and large knobs (tubercles). Pupae are found at the end of tunnels. Finally, adult shot hole borers emerge to chew exit holes and the cycle starts all over again. Adult shot hole borers are only 1/10” long and brown or black. These new adults first emerge in spring or early summer and will feed on small twigs, buds, and leaf bases before chewing a new entry hole, where they will excavate more tunnels, further weakening your trees. Entry holes are often found near lenticels. Lenticels are lens-shaped openings in the bark used in gas exchange (sort of like a breathing hole, but not really). Female shot hole borers lay up to 50 eggs. There can be 2 or more generations each year.  Shot hole borer entry hole (UCR Handout)
 Gummosis due to shot hole borer damage (USU Extension) Shot hole borer controls
Healthy trees are generally able to protect themselves against shot hole borers. This means regular irrigation to avoid water stress, proper fertilizing, depending on the age, size, and life stage of the tree, and pruning out dead and diseased wood. It also mean whitewashing trees in late winter to prevent sunburn damage to the bark. If infested wood is found, it should be removed and destroyed, to prevent the borers from spreading to healthy wood. Once shot hole borers are in the wood, there isn’t much else you can do. Insecticides are ineffective. You may be able to thwart some borers by applying sticky barriers around the trunks of your trees. Bottom line: keeping your trees healthy in the first place is a lot easier than pruning out branches and twigs infested with shot hole borers! White rust? Rust isn’t white. Rust is orange! The rust on an old car is orange. Fungal rust spores that grow on the underside of rose leaves are bright orange. Well, white rust isn’t orange or fungal.  White blister rust on mizen (Scot Nelson) White rust, white blister rust, or blister rust, is a disease that attacks plants in the cabbage family, causing white blisters, deformed growth, and leaf loss. Wet leaves and cool temperatures are all that’s needed for white rust to take hold in broccoli, cauliflower, collards, radish, and turnips. Arugula and rapini are especially susceptible to white rust. Candytuft and shepherd's purse may also become infected. White rust pathogen White rust (Albugo candida) was thought to be a fungal disease until molecular research discovered that it is caused by tiny algae-like microbes, called oomycetes, that parasitize vascular plants. Downy mildews are also caused by oomycetes. The reproductive spores created by white rust can lay dormant in soil during the dry season, waiting for the rainy season.
White rust symptoms
As flowers and leaves are infected with white rust oomycetes, white blisters (pustules) form under the plant’s skin on the underside of leaves. These blisters contain baby oomycetes. When the blisters pop, oomycete spores take to the wind, infecting nearby plants. Spores are also transferred to other plants by splashing water from irrigation or rain. These pustules appear waxy and may be pinkish, at first. Upper leaf surfaces exhibit pale green or yellowish spots that can reach 1 inch in diameter. [This disease should not be confused with chrysanthemum white rust (Puccinia spp.), which is a fungal disease and appears as masses of black, brown, purple, orange, or yellow pustules. Chrysanthemum white rust is under a CA state eradication program.] White rust controls As far as I know, there are no resistant plant varieties available (yet). Commercial growers rely on fungicides to control this disease, but you can reduce the likelihood of infection simply by decreasing the amount of time leaves stay wet. Rather than overhead watering, use drip irrigation or soaker hoses. These methods save water, too. In severe cases, an area may need to be left fallow, or you can use some serious crop rotation. Currants are a refreshing berry used to make jams, jellies, pies, and wine, but currant borers can really put a dent in your crop. In California, the invasive currant clearwing moth (Synanthedon tipuliformis) makes its appearance each April, laying eggs in bark crevices, at old pruning cuts, and in narrow branch crotches. While individual moths only live one week, overlapping generations can extend egg-laying through August. These pests bore into the canes of currants, and sometimes blackberries.  Currant clearwing moth (Whitney Cranshaw) Currant borer description Currant clearwing moths look more like wasps than moths. They have a long, narrow black body with yellow stripes. Males have four stripes; females have three. Wings are triangular and mostly clear, and the front and back wings are hooked together. Legs and antenna are long, and moths have a slightly paddle-shaped rear end. The wingspan is 1/2 to 3/4 of an inch wide. Larva are white to yellow, with brown head and legs, and a dark dorsal line may be visible. Larva look much like the American plum borer. Pupal cases are reddish brown and 3/4 of an inch long. Eggs are pale pink to red and very tiny.
Currant borer damage
When the eggs hatch, larva chew entry holes in canes, burrowing into the cambial tissue and sapwood. Here, they will feed on sap and vascular tissue for the rest of the summer, and then overwinter within the canes. In March, they will resume feeding, going through several instars, before entering a pupal stage. All this boring and feeding can girdle branches, causing twig and branch dieback. It also restricts the growth of infested plants, resulting in fewer blooms (ergo, less fruit). You may be able to see sawdust-like frass mixed with sap oozing out of entry holes, and longitudinal scars on infested twigs and branches. Currant borer controls Once a branch is infested, it should be removed and destroyed, or thrown in the trash. Severely infested plants should be removed completely. Once borers are inside a plant, there isn’t much you can do. Some people try shoving wires into entry holes, trying to stab the larva, but this is only marginally effective. Woodpeckers enjoy catching adult moths on the wing and braconid wasps parasitize these pests. There are also some beneficial nematodes that are available commercially. I’m not sure which species of nematode will work against currant borers, but you basically inject the live nematodes into the borers’ holes and spray the branches with nematodes in solution. Nematodes are fiddly and I have not had good luck with them, but they may work for you. Rather than losing valuable plants, it is far easier to prevent borer infestations int the first place. Healthy plants are better able to protect themselves against infestation, and rapid growth tends to make stems susceptible. Caring for your currant plants in a way that keeps them healthy and growing at a steady pace, rather than overloading them with fertilizer for faster growth, is the best way to prevent infestations. Also, avoid water stress with regular irrigation, especially during the peak of summer. Whitewashing the trunks of mature tree-trained currants with a 50:50 mix of water and latex interior paint can help reduce sunburn damage, which is more susceptible to infestation. Pheromone traps can be used to monitor for this pest. Just remember that the down-side of using pheromone traps is that they end up attracting pests from a greater distance. According to the U.S. Dept. of Agriculture, insecticides should be applied 7 to 10 days after the first male moth is captured in a pheromone trap. If you decide to use an insecticide, please, Please, PLEASE, follow the directions on the label exactly. Insecticides are poisons. Finally, regularly inspecting your currants and blackberries for signs of infestation can give you a unique opportunity at borer control. Just before clearwing borers emerge, they have a habit of pushing themselves halfway out of their tunnel and just sitting that way for a bit - catching their breath, I assume. So, look for areas of damaged bark and frass. If you see a borer half-way out of a twig, cane, or branch, help it out the rest of the way and then feed it to your chickens or stomp on it. Have your new seedlings been chewed off at ground level? It may be darkling beetles.  Classic darkling beetle headstand (UC Davis) Darkling beetle is the common name for all 20,000 species within the Tenebrionidae family. Some of the more famous California darklings include Blapstinus, Coelus., and Eleodes..
Darkling beetle identification Darkling beetles are dull black, blueish-black, or rusty brown, depending on the species. Unlike other beetles, the wings of darkling beetles are fused together. Some species have longitudinal ridges on their wing covers, but most are smooth, without markings of any kind. One exception is the wooly darkling beetle (Eleodes osculans), which is covered with tiny hairs. Darkling beetles can range from 1/8 to 1-1/2 of an inch long. The antennae are well developed and often have knobs at the ends (clubbed).
Darkling beetles are frequently confused with predaceous ground beetles (Carabidae), but ground beetles are shiny and their antennae are more delicate. There are other differences, but you get the idea. Darkling beetle larva look like pale yellow or dark brown wireworms. They are less than 1/3 of an inch long and are often called false wireworms. You may know one particular branch of this family as mealworms (Tenebrio molitor).  Coleoptera sp. larva/mealworm (UNC) Did you know that mealworms can digest styrofoam? Stanford researcher Craig Criddle discovered that the bacteria found in a mealworm’s gut can transform polystyrene into “carbon dioxide and recyclable organic waste.” How cool is that?!!? (UCANR) Darkling beetle behavior These pests tend to walk with their heads down and their abdomens somewhat lifted. Very often, they will stand completely still, in a headstand position, if frightened. While not dangerous, they can squirt you with a nasty smelling secretion from that rear end that does not wash off easily. This behavior is what gives some darkling beetles the name Skunk Beetle or Stink Beetle, not to be mistaken with stinkbugs. For the most part, these pests only come out at night, but you may catch one running across the patio or lawn during daylight hours. Normally, they hide under dirt clods, fallen tree bark, rocks, boards, wood chips, and in other dark places during the day. Often, the only way you know you have a darkling beetle problem is because of the damage they cause. Darkling beetle damage
In addition to attacking seedlings at ground level, darkling beetles feed on the foliage of many garden plants, such as lettuce, chicory, cabbage, broccoli, and other brassicas, beans, melons, pumpkins, tomatoes, and squash. This feeding can be seen along leaf edges and on the underside of leaves. Darkling beetles also feed on the ‘netting’ (raised areas) of melons, the flowers of most cucurbits and pistachio, and on some fruit crops, such as figs. Some species of darkling beetle also act as vectors for plant diseases and poultry parasites. Some darklings can also cause structural damage to insulation and wooden buildings. They are also attracted to poultry feed, but my guess is that the chickens make short work of that arrangement, as long as the unavailable feed is stored properly, in a metal container. Darkling beetle control Commercial farmers use insecticides to kill these pests. They also use a shallow ditch, filled with water, to block these pests from coming out of the weeds and into the fields. If you are an organic grower, as I am, you will have to use cultural controls. You can minimize darkling beetle damage organically when you:
In 2015, a report published by The Coleopterists Bulletin warned that three non-native darkling beetles have been found in California and Nevada. Each of these species is somehow tied to ant or fire ant populations:
I was unable to find any freely available photos, so you will have to track them down on your own. If you see any of these invasive beetles, please capture them and contact your local County Extension Office. You may be surprised to learn that some people keep darkling beetles as pets. If you have citrus trees, you probably have citrus mealybugs. Cousin to scale insects, these tiny pests are often overlooked. At first, all you may see is some sooty mold on a few leaves, an ant trail, marching up and down the trunk of the tree, or, finally, the telltale cluster of fuzzy white, tucked under leaves or in crevices. Left unchecked, mealybugs can scar fruit, and cause chlorosis (yellowing), early leaf and fruit drop, and poor overall tree health.  Mealybug colonies (UCANR) Citrus mealybug varieties There are actually four different mealybugs that attack citrus in the Bay Area:
Citrus mealybug description All mealybugs are soft, flat, oval-shaped critters with segmented bodies. The mealybugs that attack citrus are covered with a white wax that also creates spines (filaments) around the outer edge and the back end. Unless you use a hand lens, you probably won’t notice individuals, but mealybugs colonize areas, creating white, fuzzy egg clusters that are easy to spot. Mealybug lifecycle Male citrus mealybugs are not needed for reproduction, but they are needed by long-tailed mealybugs. When mealybug eggs hatch, the 'crawlers' are pale yellow, with red eyes, and distinct antennae. Crawlers are not born with their protective wax coating. They begin to excrete it soon after hatching. They are called crawlers because they crawl to a feeding site, where they will continue to develop (and damage fruit) for a month or two.  Adult female citrus mealybugs and crawlers (UF Extension) Citrus mealybug damage
Each female mealybug can lay hundreds of eggs, and there are usually two or three generations a year, so infestations can become a problem. As sapsuckers, citrus mealybugs pierce fruit, leaves, and young stems, to get at the sap. They also feed on tender, new growth. As they feed, they leave behind a trail of honeydew that attracts protective ants, and creates the perfect growth medium for sooty mold. Citrus mealybug feeding near fruit stems also leads to fruit drop. Citrus mealybug feeding also reduces fruit quality. Trees fail to thrive and are prone to infestation by disease and other pests. In addition to oranges, lemons, limes, and grapefruit, citrus mealybugs also have a taste for ornamental plants, such as tulips, coleus, cyclamen, begonias, and dahlias. How to control citrus mealybugs The first step to controlling citrus mealybugs is to monitor your trees, especially in spring and fall, for signs of ant trails, sooty mold, and egg clusters. Since ants will protect and farm the aphids for their honeydew, apply sticky barriers to tree trunks to block ants from protecting the aphids against their natural predators. Those natural predators are your trees’ best defense against citrus mealybugs. Ladybugs, lacewings, and hoverflies will devour these pests, so avoid using broad-spectrum pesticides. For extreme infestations, you can buy an introduced predator, called the mealybug destroyer (Cryptolaemus montrouzieri). Insecticides are not recommended. Diatomaceous earth and insecticidal soaps can be used. Mealybugs prefer dusty conditions, so hosing trees off can make them less appealing to citrus mealybugs. |
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