Mealybug destroyers, also known as mealybug ladybirds, are close cousins to our beloved lady beetle, or lady bug. In fact, many members of the Coccinellidae (kox-ih-NELL-a-DEE) family are beneficial predators, but not all. With a name like mealybug destroyers, you know that your garden plants are going to love this tiny beastie!
Mealybug destroyers (Cryptolaemus montrouzier) are native to Australia. They were brought to the U.S. in 1891 to combat California’s citrus mealybugs. Most mealybug destroyers cannot handle cold temperatures, but some populations have remained along coastal areas.
Mealybug destroyer identification
Like their close cousin, the lady bug, mealybug destroyer adults have the same dome-shaped body and short, stubby antennae. [That's a pretty cute little face, too, wouldn't you agree?] Mealybug destroyers, however, have black wing cases (elytra), with orangish-brown shoulders and rear end. Adults are only 1/6 of an inch log, so you may never notice them. If you decide to take a closer look with a hand lens, you might be able to see that females have dark brown forelegs and males’ forelegs are light brown. The larval forms, which can reach 1/2 inch in length, are often mistaken for wooly aphids or mealybugs, because of their elongated, alligator shape and waxy, white filament covering. Yellow eggs are laid near mealybug eggs for easy access to their favorite food supply.
Mealybug destroyer diet
A single mealybug destroyer may eat 250 mealybugs in its short lifetime. They also feed on soft scale insects. And it is not just the adults who hunt down and kill our garden enemies. While adults chomp and chew, larval forms pierce and suck the life juices from many sap-sucking garden pests.
So, why would a gardener care about mealybugs? Cousin to aphids and whiteflies, mealybugs are sap eaters. They feed on new buds, shoots, and leaves, causing erratic or reduced budbreak, slowed growth, and twig dieback. Mealybugs are frequent pests to basil, grapes, stone pine, pomegranate, chamomile, apple, plum, pear, peach, ferns, orchids, and, well, quite honestly, pretty much everything growing inside or outside of your home. Mealybugs produce honeydew, which provides the perfect growth medium for sooty mold. They can also carry bean mosaic. That’s why.
Attracting mealybug destroyers
It is highly unlikely that there are any mealybug destroyers in your neighborhood to attract. They simply cannot handle winter weather. So, you will probably have to buy mealybug destroyers each spring. What you can do, to prevent them from flying away as soon as they arrive, is to provide biodiversity. This means installing a wide variety of plants, with various heights, shapes, and colors. And avoid those broad spectrum insecticides.
Mealybug destroyers may not occur naturally in the Bay Area, but they sure can help maintain the balance of power in your foodscape!
Flea beetles hop from plant to plant, chewing tiny holes in leaves as they go.
We are not talking about the blood-sucking, disease-carrying fleas on squirrels. Instead, flea beetles are plant pests. Generally, they do not cause a lot of damage. After all, each flea beetle is only 1/16 to 1/8 of an inch long! If your plants are hosting enough of them, however, the damage can slow growth or provide points of entry for bigger problems. Let’s see what your plants are up against.
Flea beetle varieties
There are dozens of leaf beetle species. Here in the Bay Area, you are more likely to see these particular pests:
Flea beetle host plants
Flea beetles feed on many families of edible garden plants:
Also, carrots, corn, and sweet potatoes may find themselves on the menu. Flea beetles are also attracted to yarrow, but this is a good thing. Yarrow acts as an insectary. Beneficial insects have evolved to lay their eggs in plants such as yarrow, knowing that flea beetles and other pests will provide their young with an easy first meal. Other beneficials, such as big-eyed bugs, will also feed on flea beetles, so go easy on the pesticides. Pesticides don’t work very well on flea beetles anyway - they simply hop away.
Flea beetle damage
Pitting and small, irregular holes in leaves may merge to create raggedy areas. The holes are smaller than the damage caused by shot hole disease. Shot hole disease holes usually begin as 1/10 to 1/4 inch diameter red or purplish spots. There may be a pale green or yellow ring around each spot. As the dead tissue dries up and falls away, the shotgun blast look will appear. Small, irregular leaf holes may be caused by springtails, but it is more likely to be flea beetles. Fruits and roots may also be damaged by flea beetles.
Flea beetle lifecycle
Flea beetles lay tiny eggs in weeds, plant debris, and in the soil surrounding their favorite food plants. After the eggs hatch into thin, white larva, feeding may begin above or below ground. After a month or so, the larva pupate in the soil. When they emerge as adults, they use their big jumping legs to go wherever they want to feed.
Flea beetle control
Since pesticides are not very effective on flea beetles, other controls must be used, if control is actually needed. In most cases, it isn’t. If an infestation starts to cause serious damage, use basic sanitation in the garden. Removing all those tiny hiding places can make life difficult for flea beetles. Reflective mulch and white sticky traps can also be used, and row covers may block pests from reaching plants in the first place. Once they are present, you can lightly sprinkle the area with diatomaceous earth (DE). Apparently, flea beetles don’t care too much for sulfur, either.
Some commercial growers actually vacuum off heavy flea beetle infestations, but I don’t recommend it for the home gardener. You vacuum cleaner would never be the same!
Phoresy describes the relationship between two organisms in which one is a hitchhiker, but not a parasite.
The fleas that catch a ride on your dog or cat are parasites. They catch rides and then drink the blood of our beloved pets. This is not phoresy. Now, picture a person riding a horse. Person plus horse equals phoresy. The person is being transported by the horse, but is not a parasite.
In many cases, electron microscopy is needed to actually see phoresy in action. And many phoretic insects lose the ability to catch a ride once they have reached a destination. Like many other insects, those that use phoresy may go through several very different life stages, such as phoretic, parasitic, and reproductive stages.
In nature, phoresy can bring both pests and beneficials to your garden. Here are just a few of the situations in which phoresy occurs.
We may love to see hummingbirds flitting through the garden, but you should be aware that hummingbirds may carry flower mites. Flower mites are tiny, nectar stealing pests that run up a hummingbird’s beak as it feeds. Grabbing ahold of the hummingbird’s nostrils, flower mites then go for a wild ride in hopes of reaching a new food source. When the hummingbird stops to feed at a different flower, the mite runs down the hummingbird’s beak to gorge on as much nectar as it can before hopping another ride to yet another flower.
Moving in the opposite direction, it has recently been discovered that varroa mites, the bane of honey bees, are phoretic. These devastating parasites of the honey industry lie in wait for unsuspecting honey bees to visit a flower. As the bee collects nectar and pollen, varroa mites catch a ride that ultimately takes them to the hive. These parasites suck the life fluids from developing and adult bees. These pests also carry viruses that infect honey bees. Varroa mite infestations can kill an entire hive, if left untreated. Varroa mites are just one aspect of the global problem of colony collapse disorder.
Male ground bees are seduced by blister beetle larvae into carrying them to female ground beetles, phoresy style. Blister beetle larvae emit a pheromone that is similar to the perfume used by female blister beetles to attract males. When male ground bees approach, the blister beetle larvae attach themselves to the male bees. After recovering from their disappointment, the male bees continue their search for a female. When she is found, the male bee blindly does his business as the blister beetle larva moves to the female bee. When she returns to her nesting area, the larva jumps off and begins feeding on everything it can - nest, provisions, and eggs.
Pseudoscorpions are tiny beneficial insects that feed on ants, thrips, small flies, springtails, carpet beetles, clothes moth larvae, booklice, and spider mites. They also get around using phoresy by catching rides on many different flying and crawling insects. In some cases, they even provide a service to the carrier insect by eating its parasites along the way!
One phoretic wasp, Trichogramma, catches rides on mated female imported cabbage moths to reach areas where eggs have been laid. These beneficial wasps then parasitize the eggs, making our jobs as gardeners so much easier. Research on this behavior is new, but very exciting!
Greenhouses provide the warmth, sunlight, and moisture that plants need to thrive. The same is true for thrips, whiteflies, leafhoppers, and fungus gnats, just to name a few. While reputable greenhouse growers do their best to eliminate pest phoresy on the plants they sell, it still happens. Many imported pests and diseases are brought into new areas through phoresy. When you bring plants home, you also risk bringing phoretic pests and diseases. This is why it is so important to create a quarantine area. Forty days and nights goes a long way toward sorting out and preventing more serious problems.
So, quit "phoresing" around! Go take a closer look at your plants and the insects that call them home. You may be surprised to see what’s out there!
Clubroot is not the newest bar in town; it is a disease of many fall and winter crops.
Clubroot, or club root, is caused by an imported plant parasite that grows inside of plant cells. This parasite used to be classified as a slime mold, but is now in an entirely different category, called Phytomyxea. This pathogen is called Plasmodiophora brassicae, but don’t let the name scare you off from learning about it. The brassicae part of the name tells you which plants are susceptible: members of the cabbage family. The Plasmodiophora part of the name tells us that these are mouthless, amoeba-like plant parasites.
Which plants are affected by clubroot?
Clubroot occurs in nearly all members of the brassica family. This means that your broccoli, Brussels sprouts, cabbages, cauliflower, radishes, and turnips are susceptible. In addition, alyssum, mustard, nasturtium, and wallflowers, as brassicas, can also become infested with this parasite.
Symptoms of clubroot
At first, there may not be any aboveground symptoms to clue you in to this problem. Leaves may begin to wilt or look stunted. They may yellow. Of course, those symptoms could be any number of issues: water stress, nematodes, thrips, aphids…it’s a long list But, if you were to dig the plant up and look at its roots, well, that would be a different story altogether. Roots infested with clubroot parasites are covered with galls (ulcerations). They are also distorted and swollen, interfering with the transfer of water and nutrients that keep the plant alive. One look at the roots and you will know that something isn’t right.
Once this micro-critter is in your soil, it may never go away completely. Soil solarization is the only sure way to get rid of it, and that only works if the solarization is done properly. Use these tips to reduce the chance of clubroot occurring in your garden:
When it comes to clubroot, prevention is worth the effort.
Don’t get your hopes up. Chocolate spot is a fungal disease that attacks fava and other broad beans.
Chocolate spot is caused by the Botrytis fungi, a family of fungi responsible for grey mold on practically everything. Chocolate spot, in particular, is caused by Botrytis fabae.
Chocolate spot symptoms
Moist conditions cause small reddish-brown spots to form on leaves and pods. These spots expand, leaving a dead, gray center. The fungi can spread so much that leaves and pods are aborted. And they certainly don’t look very appetizing!
How to control chocolate spot
As always, avoid overhead watering on plants susceptible to fungal disease. Black aphids are suspected carriers of the fungi that cause this disease, so controlling aphid populations may help. These fungi can overwinter in the soil and on decaying plant debris. Be sure to remove any infected plant material completely from the garden to avoid spreading the disease. Fungicides have been used to control chocolate spot, but timing is critical.
Carrot beetle damage
Carrot beetles (Ligyrus gibbosus) feed both above and below ground. They attack sunflowers, carrots, lilies, iris, and dahlia. Taproot feeding causes yellowing foliage (chlorosis), stunting, plant collapse, and death. Feeding damage may also be seen on lower (basal) leaves and stems.
Carrot beetle control
Adult beetles fly at night and are attracted to lights. You can reduce infestation by using row covers and keeping the garden unlit at night. You can also reduce hiding places by keeping mulch and decaying plant matter away from susceptible plants. Insecticides have not been effective at controlling these pests.
Adult carrot beetle (Frank Peairs)
Dodder is too bizarre for words.
This plant doesn’t even look like a plant. It looks more like a fungi, or an alien!
Thin yellow, red, or bright orange threads emerge from the ground and start twining around and draping over everything in sight. Everything, that is, if you’re a plant. Dodder (Cuscuta) is a parasitic annual. It gets most of its nutrition by inserting a straw-like structure, called the haustoria, into the plants it covers. Some species of dodder can perform a limited amount of photosynthesis.
The dodder plant
If you look closely, you can see that dodder seedlings are rootless, leafless stems. As the dodder plant matures, it may produce small, triangular leaves that look like scales. Tiny, bell-shaped, cream, pink, or yellow flowers may also be seen, but it is the extensive web of threads that will really catch your eye!
Dodder in the garden
You will probably never see dodder in your garden or landscape, but it’s possible. Different dodder plants may attack marjoram, tomatoes, beets, melons, or asparagus plants from mid-summer through early autumn.
Getting rid of dodder is problematic. If you find it in your garden, ask for help from your local Master Gardeners. If you discover Japanese dodder ANYWHERE, contact your county agricultural commissioner. This new invasive is under a statewide eradication program.
Bacterial wilt is a disease that causes members of the gourd family to wilt.
Bacterial wilt is caused by a bacterium called Erwinia tracheiphila. It mostly affects cucumbers and muskmelons, but it can also infect pumpkins and squash.
Symptoms of bacterial wilt
Damage caused by bacterial wilt looks a lot like feeding damage caused by squash bugs. As the bacterium begin to multiply within vascular tissue (veins), they clog the xylem, which makes the plant wilt. The sap of an infected plant will be milky colored and able to create a viscous string. (Ew!)
Striped and spotted cucumber beetles carry this disease. The Erwinia bacteria that cause this disease can live in the gut of their carriers for quite a long time. The bacteria can be transmitted as these pests feed and through contact with frass.
Bacterial wilt treatment
Unfortunately, there is no effective treatment. Once a plant is infected, it is too late. Since the infected plant poses a health risk to its neighbors, it should be removed and thrown in the trash. Any tools that came into contact with the plant should be sanitized in a solution of one part bleach and nine parts water. Bathroom disinfectant can also be used. To reduce the chance of infection, controlling beetle populations and maintaining healthy plants are your best bet.
Bright yellow pests on milkweed? It’s oleander aphids!
Many of us have planted region-specific milkweed plants to support Monarch butterfly populations. What we didn’t know, was that we would also be inviting a new pest into our gardens: oleander aphids. These pests can suck the life out your milkweed plants before the Monarchs ever have a chance.
Oleander aphid description
Like other aphids, this species is small (1.5 to 2.6 mm), pear-shaped and soft-bodied. Oleander aphids, in particular, are bright yellow, with black legs, wings, and cornicles. Cornicles are tiny spikes on an aphid’s back that can excrete defensive fluid. [My dog did that once, after he got into some old pork bones. It wasn’t pretty.] Actually, these defensive fluids are cardiac glycosides that the aphids take from their host plants! Cardiac glycosides are known heart poisons. Luckily, these pests cluster on new stems and are easy to spot. And those defensive fluids won’t hurt you.
As much as I dislike aphids for their plant-damaging and disease-carrying capabilities, I have to give credit where it is due. These soft-bodied bugs really are amazing. Female aphids (and almost all of them are female) are viviparous and parthenogenetic. Wait! Come back! Let me explain. Viviparous means that offspring develop within the mother, the way we do. Parthenogenetic means fertilization by a male is not needed to produce offspring. Not like us. Most aphids do not have wings. But, when they become too crowded, or when a plant starts senescing (dying), some adult aphids emerge with wings. That would be something like all human beings being born 40% smaller, simply because we start running out of room and resources. Hmmm… But I digress. Let’s get back to aphids.]
Oleander aphid damage
Like other sap-sucking insects, oleander aphids pierce plant parts to tap into the phloem of the host plant. Think of it as diabetic mainlining. This nutrient rich food source blows through an aphid’s body, creating a sticky sweet residue called honeydew. Honeydew is a petri dish for bacterial and fungal growths, such as sooty mold. Also, the aphid tendency to feed in clusters stunts growth and deforms flowers and leaves, crippling milkweed and oleander plants. Vinca, periwinkle, and frangipani are also affected.
Oleander aphid management
If you’re not squeamish, you can squish the aphids between your fingers. Or, if you see a stray lady beetle wandering around elsewhere in the garden, gently scoop them up and show them where the feast can be found. If those are not options, you can use a strong spray of water from the hose to dislodge the interlopers, or make your own insecticidal soap. Do this by combining one gallon of water and one teaspoon of liquid dish soap. Do not shake. It will take too long for the bubbles to subside. It is much better to stir or gently roll the solution around in a clean, repurposed plastic jug. Then, put the solution in a spray bottle and let ‘em have it! On plants with heavy stalks, you can interrupt support for aphids from ants by painting the stalk with a sticky barrier. This won’t get rid of the aphids, but ti will make them more vulnerable to their natural enemies.
Unfortunately for the Monarchs, nearly all of these methods will harm their offspring along with the aphids. Lady beetles will eat Monarch eggs and larva, the soap will kill them, as well. There is a parasitic wasp, Lysiphlebus testaceipes, that feeds on oleander aphids, as do syrphid flies, so avoid those broad spectrum pesticides. If you see dried up, brown husks of aphids, you will know that you have these helpers in your garden.
Katydids are cousins to crickets, grasshoppers, and mole crickets, and you do not want them in your garden or landscape.
There are over 250 different species of katydid in North America (over 2,000 species worldwide). The name ‘katydid’ refers to the sound made by males when they are trying to attract receptive females.
Katydids can be difficult to see. It’s not that they are small, because they aren’t. Mature katydids can range from 1/2” to nearly 5” in length! The difficulty lies in their resemblance to leaves and the fact that they are mostly nocturnal. During the day, they hide out in trees and shrubs, blending with the foliage. They tend to have a bright green, blade-like body, with large hind legs. They look a lot like flattened grasshoppers, but with extra long antennae (or ‘horns’). Very often, the only notice you will get that katydids are present is the damage they cause and a male’s strident chirp.
Katydids (Tettigoniidae) start out as oval-shaped eggs that are laid in rows, at the end of summer, in the soil and in host plant stem holes. These eggs often hatch out looking like tiny adult katydids with big heads and small wings. Nymphs of some species of katydid mimic spiders or leaf-footed bugs in their early stages of development to avoid being eaten. As they feed and grow, they shed their outer exoskeleton and go through several instars before reaching adult size. As summer nears its end, males start singing to attract females. Females use the volume and fluency of a male’s chirp to judge his fitness level. In order to ensure a healthy pregnancy for the female, male katydids provide their (temporary) mates with a ‘nuptial gift’ of sperm and highly nutritious food.
Katydids bite and chew many different plant parts, including leaves, stems, seeds, bark, buds, flowers, roots… okay, pretty much every part of a plant is vulnerable to katydid feeding. The damage often looks like it was caused by caterpillars or grubs. Citrus, peaches, pears, blueberries, apricots, plums, and pomegranates are just a few of a katydids menu items.
These pests are super fast, and difficult to catch. I use a butterfly net to catch them, and then I feed them to my chickens, who are very happy to help reduce my garden’s pest populations. Commercial growers often use spinosad to control katydids. I have read that katydids can inflict a painful bite or pinch, but I never give them the opportunity. Apparently, in Uganda, people eat katydids.
Katydids as thermometers
If you hear a katydid, you can estimate the ambient temperature using Dolbear’s law. According to Amos Dolbear’s 1897 calculations, you can count the number of cricket chirps that occur over a 15 second period and then add 40 to that number for a reasonable estimate of temperature. If you are using katydids for this experiment, it is suggested that you add 37, instead of 40.
If you hear katydids in the garden, go get your butterfly net and start hunting! These suckers can reproduce exponentially!
Buffalo hopping from tree to tree? The image made me laugh, so I decided to make this pest the Garden Word of the Day.
Buffalo treehoppers (Stictocephala bisonia) get their name because they have a triangular head that looks like a buffalo in profile. Sort of. These native pests are only 1/4 inch long and bright green to brown. Because of the color and shape, they are difficult to see. Some individuals develop a horn-shape to the head that looks like a thorn. You can walk right up on one and not even know it’s there, until it leaps into the air and flies away.
Buffalo treehopper lifecycle
Every summer, male buffalo leafhoppers take to the trees and sing their tiny hearts out, but we can’t hear them. If we could, they would sound something like cicadas, or crickets. His song attracts females for the normal reproductive activities. Late summer through early autumn, females lay eggs using a blade-shaped ovipositor that cuts a series of slits in twigs and stems. Each cut may contain a dozen eggs. The next year, in late spring, nymphs emerge. They look like miniature adults, but with feathery spines. After several molts, they emerge as adults.
Damage caused by buffalo treehoppers
Well, they break off entire branches, right? Just kidding. These small pests begin their destructive behavior during the nymph stage when they drop to the ground and feed on grasses and herbaceous plants. As they mature, they begin feeding on many different fruit trees, particularly apple, pear, cherry, prune, and quince. They also feed on ash, hawthorn, elm, and locust, and a wide variety of herbaceous (non-woody) plants.
All stages of buffalo leafhopper are sap-suckers. They use piercing mouthparts to tap into the phloem for a sugar feast. This feeding results in a sticky sweet discharge called honeydew. Buffalo leafhopper damage is minimal, but big populations can cause problems with sooty mold fungi feeding on the honeydew.
Buffalo treehopper controls
Since they hop like crazy and can fly, control is difficult. A strong spray from a garden hose can dislodge insects from a specific host (for a while). While not nearly as interesting as trying to round-up a herd of forest-dwelling bovines, insecticidal soaps are effective. The best treatment you can give plants being sucked dry by buffalo leafhoppers is to hose them down to wash off the honeydew.
The heady aroma of summer nectarines and peaches means it’s time to be on the lookout for peach twig borers.
While examining my nectarines for ripeness, I spotted a reddish-brown larva with white bands undulating across a twig. Of course, I picked it up and dropped it in a little plastic bag and sealed it up tight, until I could look it up. That’s what I learned that even the nicest tree cage has its limits.
Peach twig borer description
The reddish brown larva I saw was relatively mature. They hatch out white with a black head. As they feed, the color darkens. Unlike other larval pests of peaches, the peach twig borer has white bands around its abdomen, though the bands are not always as obvious as they are in the photo above. The pupae are 1/4 to 1/2 inch long and brown. They do not have a cocoon. Adult moths are small, slender, and a mottled grey color, with fringed wings and a false snout. Oval eggs are yellowish-orange and laid on fruit, twigs, and leaves.
Peach twig borer control
Tachinid flies and braconid wasps provide natural controls. When that isn’t enough, you can spray environmentally sound insecticides, such as Bacillus thuringiensis (Bt) or spinosad, just as blossoms appear, for added peach twig borer control. Dormant oil can also be used in winter, when combined with the same insecticides, to kill off the overwintering larvae. The oil will not kill peach twig borers by itself. Pheromone traps can be used to interfere with mating and to monitor for these pests. Just be aware that hanging a pheromone trap can actually attract pests to your trees if handled incorrectly. Read the label.
So, as you check your nectarines and peaches for ripeness each summer, be on the lookout for these tiny pests. Also, add preventative treatments to your garden calendar while you’re thinking about it.
The summer song of crickets and grasshoppers provide many of us with a comforting reminder of childhood. If you are a gardener, your might hear those sounds with different ears.
Cousins to katydids and locusts, crickets (Gryllidae) and grasshoppers (Acrididae) are members of the Orthoptera family.
Both crickets and grasshoppers have a large head, long saltatorial* back legs, for jumping, a cylindrical body (pronotum), compound eyes, and a mouth able to bite and chew. They have two pairs of wings: the forewings (tegmina) and hindwings. Beyond those similarities, there are many differences:
Lifecycle of crickets and grasshoppers
Both species start out as eggs that were laid, in late summer and early fall, in the top 2 inches of soil, in clusters of 20 to over 100 eggs. In spring, these eggs hatch as nymphs, which begin feeding on nearby plants. When those food supplies are exhausted, they look for new places to feed, generally downhill from where they started. Grasshoppers will molt 5 or 6 times as they outgrow their exoskeletons, and crickets molt 8 or more times. There is no pupal stage, so these insects are said to go through incomplete metamorphosis.
There are house crickets and field crickets. Both are collective terms for several different cricket species. All of them feed on seeds and plants, along with grasshopper eggs, moth and butterfly pupae, flies, and spider sack lunches. House crickets (Acheta domesticus), sold as lizard food, are usually brown or tan, and one inch long or less. Field crickets are slightly larger than house crickets and they are usually black.
While there are over 200 different types of grasshoppers in California, only two cause significant damage: the valley grasshopper (Oedaleonotus enigma) and the devastating grasshopper (Melanoplus devastator). Most grasshoppers can fly.
Cricket and grasshopper damage
If their song didn’t tell you these pests had arrived, chewed holes in leaves certainly will. Grasshoppers and crickets will often hide out in nearby weeds and brush, so keeping those areas mowed can reduce the likelihood of a visit. On the flip side, maintaining a lush, green border may provide all the feeding that is needed by a few individuals. In any case, a single cricket will not do significant damage, but a large number of them can decimate a row of seedlings in just one night. Grasshoppers prefer green plants, so your lettuce, onions, carrots, corn, beans. melons, squash, and some annual flowers are vulnerable. Grasshoppers may also feed on citrus, avocado, and beets. In years with especially wet springs, cricket and grasshopper populations can explode. In these years, food scarcity makes all plants vulnerable.
Grasshopper and cricket controls
If these insects are causing damage in your garden or landscape, floating row covers, screened boxes, and cones are your best bet. Just be sure there are not any individuals hiding out in the mulch around your plants, or you may create a virtual Club Med for the pest! Birds, robber flies, and blister beetles feed on crickets and grasshoppers, or their eggs, and many parasites, bacteria, and fungi attack these garden pests. You can hand pick them if you are quick enough. Chickens are excellent at catching them, and it’s a riot to watch.
* For you word game and vocabulary nerds, saltatorial is an adjective that describes the legs of jumping insects.
Bacterial speck may sound redundant - we all know bacteria are tiny - but bacterial speck is a bacterial disease of tomatoes that can be controlled with a speck of good cultural practices.
Bacterial speck looks a lot like bacterial spot and bacterial canker, but it is less likely to be fatal. All three diseases appear as small brown or black lesions on leaves, stems, and fruit. These lesions may merge into larger, irregularly-shaped areas. There is normally a yellow halo around these lesions and the interior tissue dies rather quickly. Most of these lesions are found near leaf edges (margins). On fruit, the lesions look like tiny black bumps.
Bacterial speck lifecycle
Bacterial speck is caused by Pseudomonas syringae pv. tomato, a cousin of the bacteria that cause angular leafspot, citrus blast, and leaf spot. This bacteria is found in soil and on seeds. Seeds from diseased fruits should not be planted the following season, or you will simply continue the process in your garden. These bacterium can remain dormant for a very long time, until the weather turns cool and damp. Then they start growing like crazy. The bacteria are frequently splashed onto leaf surfaces by rain and overhead watering.
Bacterial speck control
Fixed copper sprays and good air circulation are your best preventative measures. You can also delay spring planting until after temperatures warm up, and avoid overhead watering. Properly spacing plants can reduce the spread of infection.
Diseased fruits are safe to eat, simply cut out the infected areas and toss them in the trash (or feed them to your chickens). Diseased plants should not be composted. Instead, toss them in the garbage to reduce the likelihood of reinfection.
Blight is a symptom of plant disease.
One day, your plant looks lush and healthy. The next day, several leaves are yellow and then turn brown. Stems, flowers, and branches also turn brown and then die. What can cause this sudden, severe damage? It might be blight.
Blight is a symptom
Blight is not a disease. It is what several different plant diseases look like. The initial symptoms appear suddenly and spread very quickly. Leaves, fruit, stems, and flowers can all be affected. The first symptom is tiny lesions on leaf tissue. This is where the bacteria or fungi first enter the plant, usually through small tears. The pathogens may also enter through vulnerable new growth. What starts out looking like leaf spot soon covers entire areas of a plant. Leaves and flowers suddenly lose all their green and turn pale yellow (chlorosis), followed by spotting, browning, withering, and dying.
Blight is most commonly seen on tomatoes and potatoes (nightshade family), and on apples and pears (pome fruits). Ornamental plants are not exempt. Here is a list of the most common blight diseases:
How to control blight
Since blight enters plants through wounds and tender new growth, there are three ways you can reduce the likelihood of blight occurring in your garden:
These are especially important when temperatures of 75° to 85°F are expected to be accompanied by rain. Pruning and feeding stimulate new growth that cannot defend itself. Also, do not irrigate trees while they are in flower. Monitor plants closely after favorable conditions have occurred and completely remove and destroy any infected tissue. This means cutting several inches below infected tissue, using pruners that are dipped in 1 part bleach and 9 parts water between each cut. This reduces the spread of the disease. Blossom sprays can be used on trees that have experienced blight in the past. Fixed copper sprays may provide some protection.
Boing! A tiny insect launches itself and you never really see it clearly.
It’s probably a leaf hopper. Let’s learn about these garden pests so we can reduce the damage they cause.
Leafhoppers are cousins to treehoppers and cicadas. The name “leafhopper” actually refers to twenty thousand different Cicadellidae insects. Most leafhoppers feed on a specific plant or group of plants. Eggs are laid in soft plant tissue, where they overwinter. Eggs begin to hatch in mid-April in the Bay Area. These wingless nymphs will molt several times, each time their wings and hind legs getting larger and more functional. What makes leafhoppers particularly unique is that they cover themselves, after each molt, with a microscopic body armor made out of netted spheres called brochosomes. [It's one of those 'stranger than fiction' realities, isn't it?]
This armor keeps them dry and protects them from their own sugary excrement. Brochosomes are also believed to protect them from enemies, as well, but no one is really sure. What I am sure of is that leafhoppers are unwelcome in my garden and landscape, and here’s why:
Leafhoppers eat sap and, as they feed, they spread disease.
Plants preferred by leafhoppers
Leafhoppers enjoy many of the same plants that we do. In addition to many woody ornamentals, such as boxwood, local leafhopper species love to feed on sweet potatoes, squash, beans, horseradish, cucumbers, corn, melons, blueberries, grapes, and beets, just to name a few! Since leafhoppers can carry diseases with them, they put many plants at risk.
Leaf stippling is usually the first sign of leafhopper infestations. This damage is normally at its worst in July and August, in the Bay Area. While leaf stippling won’t harm a healthy plant, it does interfere with photosynthesis and it can compound water stress. Leaves may also appear pale or brown, and new shoots may curl up and die. As they feed, some leafhopper species produce honeydew, which provides the perfect growing medium for sooty mold. Also, leafhoppers are vectors for several plant diseases, including aster yellows, bean mosaic, and vivipary.
Since they are so mobile, complete control is pretty much impossible. Spiders, assassin bugs, and lacewings all eat leafhoppers, so avoid using broad spectrum pesticides that will kill off these beneficial insects. Severe infestations can be treated with insecticidal soap or horticultural oil, just be judicious with the application since oils can contribute to sunburn damage. These treatments are only effective on nymphs.
So, if you walk by a plant and get pelted by a bunch of tiny bugs, or you notice a lot of leaf stippling, take a closer look - it may be time for a spray of soapy water.
Belly rot looks almost as bad as it sounds.
What starts as brown or black mushy areas on the underside of your melons or squashes turns dry and leathery. It won’t hurt you, but it can make fruits more susceptible to other pests and diseases.
Melons, squashes, and other members of the cucurbit family can all get belly rot. Belly rot is a fungal disease caused by Rhizoctonia solani. Infection occurs when fruit is left to sit on the soil for prolonged periods, especially when moisture is present.
Symptoms of belly rot
If you see water-soaked, sunken, black or brown spots on fruit, and it is not blossom end rot, it is probably belly rot. The lesions can be very small to covering the complete underside of a fruit. As the infection spreads, the lesions dry out and become leathery or scabby. Infected fruit should be removed
Preventing belly rot
To prevent the spread of belly rot, avoid overhead watering and get that fruit up off the ground. You can use trellising, tomato cages, children’s furniture, those little plastic pizza box props, straw, benches, colanders - ANYTHING that will allow some air to get between the fruit and the soil. Improving drainage will also make this disease less likely to occur.
Generally, the fungi that cause belly rot are everywhere, so prevention is your best bet. This means checking the bellies of your melons on a regular basis!
Braconid wasps are tiny heroes of the garden, though rarely seen.
The list of edibles protected by braconid wasps is too long to include here, but it would include grapes, peaches, nectarines, apricots, tomatoes, apples, prunes, plums, broccoli, rutabagas, turnips, and cabbage, just to name a few.
Braconid wasp identification
There are over 12,000 different named braconid wasp species, worldwide, with another 40,000 or so, yet to be identified. Most are dark brown or black with reddish accents. It is estimated that there are 1,700 different braconid wasps in North America and they are all stingless. Braconid wasps can be as small as 1/13 of an inch long, or as big as 5/8 of an inch. If you can get one to hold still while you go find a hand lens, you would be able to see that these tiny wasps have antennas with 16 or more segments! What you are more likely to see are their oblong, white or yellow eggs sticking out of a host insect.
Braconid wasp diet
Adult braconid wasps, while they eat mostly pollen and nectar, are beneficial because they parasitize many garden pests. This means that they lay their eggs on or in other insects. When the eggs hatch, the larvae eat their host. Garden pests vulnerable to parasitization by braconid wasps include:
Attracting braconid wasps to your garden
Parasitic and predatory wasps are attracted to mixed plantings that provide nectar and pollen, along with insect prey. To make your garden and landscape more appealing to these beneficial insects, be sure to include a wide variety of flowering plants at various stages of development throughout the growing season.
What’s that grey mold that appears overnight on your strawberries? Where did it come from? And how did it happen so fast? Strawberries can go from nearly perfect to practically inedible in an astoundingly short time. Read on to find out why!
Botrytis cinerea is everywhere. It flies in on the wind, it is carried on clothing, shoes, tools, pets; it’s floating around in the air we breath. Yep, it’s like that. So, unless you live in a bubble, your plants and food are already in contact with grey mold. There are actually several different strains of grey mold. They get their Latin name, Botrytis, from the Greek words for ‘grapes like ashes’. You might think that’s because they feed on grapes, but it is actually because the fungi itself grows in clusters. The word ‘ash’ refers to the grey color.
This particular garden problem spends most of its time as a dormant, asexual spore that is relatively indestructible. Add moisture in spring (or with irrigation) and voilà, stuff starts to happen!
Grey mold - This is the gray fuzz we find on our strawberries, grapes, and other fruit and flowers.
Noble rot - If dry conditions follow wet weather, the fungi suck moisture out of grapes, leaving behind a bitter aftertaste.
Antifungal - If that weren’t bad enough, botrytis also interferes with wine-making! As it grows, it produces an antifungal substance (presumably to kill off the competition) that also kills off the yeast that makes grape juice magically transform into your favorite Chardonnay or Pinot Noir.
Bunch rot - As soon as an injury occurs to grape vines or fruit, the botrytis fungi cause bunch rot infection.
Most commercial grape growers apply fungicides to prevent infection, since the fungi is present all the time. As wth downy mildews, black spot, and powdery mildew, moisture control is the key. If leaves and fruit are left wet, they are more likely to become infected. [Remember those strawberries you washed before putting them in the fridge last night? Yep, that’s what happened!]
Controlling grey mold
Once infection begins, potassium bicarbonate-based fungicides can be applied to reduce the spread of the disease. Dead and diseased plant tissue should be carefully removed. I say ‘carefully’ because each bit can contain millions of fungal spores.
Some people have an allergic reaction to grey mold that causes a rare lung disease known as ‘winegrower’s lung’.
So, the next time you buy strawberries or grapes, wait until you are ready to eat them before rinsing them off. It’s not a guarantee, but it helps! Also, keep them in their container and put them in the crisper drawer. Strawberries are best stored at 32 to 36 degrees F, at 90 to 95% humidity.
Black spots on leaves and petals is a sign of disease.
Spring and summer fogs and dew can leave behind just enough moisture to create breeding grounds for several different bacteria and fungi. While there is a specific disease called black spot, there are other bacterial and fungal diseases that can cause black spots, including citrus blast, common leaf spot, bacterial spot, anthracnose, bacterial speck, and entosporium leaf spot. Black spot mostly attacks roses, but its presence can indicate potential other problems in the garden or landscape.
What are the black spots on my leaves?
Black spots on leaves, fruit, canes, stems, and twigs are areas where a pathogen is breeding and feeding on plant tissue. These black spots are generally round because the infection begins at one point and spreads out equally in all directions. The spots have perforated edges and can reach one-half inch in diameter. As the area of dead tissue expands even larger, it can take on many different shapes. There may be a yellow halo around these leaf spots and yellowing in the surrounding plant tissue.
Black spot: the disease
The black spot disease is caused by a fungus called Diplocarpon rosae. These fungi spread through rain and sprinkler splash, and wind, to tender new growth. This disease usually spreads from lower leaves, moving upward. Tools used on an infected plant can also spread the disease to other plants, so be sure to sterilize tools with a 1 part bleach, 9 parts water solution, or spray tools with bathroom cleaner after each cut when working with a potentially infected plant.
Black spot treatment
Once a leaf is infected, there isn’t anything you can do for it except remove it from the plant and throw it in the trash. Antifungal sprays, such as Bordeaux mixture, can be used to prevent future infection and at the first sign of the disease. Sulfur or diluted neem oil can also be used. Treatments will need to be repeated every 7 to 10 days for as long as temperatures are between 75 to 90 °F.
Preventing black spots
As usual, prevention is a lot easier (and more effective) than treatment. These tips can go a long way toward preventing the problem of black spot in the first place:
I hope this information inspires you to grow more of your own food. You can ask your garden questions on my Home page.