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.
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.
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:
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!
Lucious fresh blueberries in California? Yes, you can!
While blueberries traditionally grow in colder climates, there are varieties that grow successfully in warmer temperatures.
There are three main types of blueberry plant: southern highbush, northern highbush, and rabbit eye. Southern highbush and rabbit eye varietals often perform well in higher temperatures. Generally, the northern highbush types need more chilling hours than the Bay Area can provide. Even when they do grow, the fruit often lacks good flavor. Also, the northern highbush types will take longer to start producing fruit in warmer areas. Two popular southern highbush varieties for the Bay Area are Southmoon and O’Neal. Santa Clara County Master Gardener offer this list of blueberry plants that perform well in warmer climates.
Prepare for planting
Blueberry plants are nearly always sold as 1-gallon yearlings.These young plants will benefit from 7 to 10 days of acclimation, or hardening off, after growing in a greenhouse. Be sure to keep the soil moist but not soggy. The root system is a hairy ball that should never be allowed to dry out completely. If it does, the plant dies. At the same time, too much water can set the stage for fungal disease. Yeah, I know - picky, picky, picky! Of course, once you start picking scrumptious blueberries off your very own edible hedge, you’ll realize it’s well worth the effort.
How to grow blueberries
So, choose the best varieties for your microclimate and taste. Even though most blueberry plants are self-pollinating, you will get a substantial increase in both fruit quantity and quality through cross-pollination with multiple plants. Plants should be spaced 4 to 6 feet apart. Blueberries perform best with 6 to 8 hours of sunlight each day, so select the site accordingly. Good drainage is important, too, so be sure to amend the planting area with plenty of aged compost. This is critical in the Bay Area, because blueberries do not particularly care for our heavy clay. Plants should be placed with the crown at soil level. Since blueberries have a shallow root system, you can help them stay happy and healthy by mulching and watering regularly in summer. Blueberries can also be grown in containers.
Blueberries seem to prefer ammoniacal nitrogen based fertilizers over nitrate based. I have heard tell that blueberries do not take up the nitrogen in nitrate based fertilizers. Too much nitrogen can burn blueberry plants, so do not feed until leaves have emerged, and then feed sparingly.
Acidifying blueberry soil
Blueberries prefer a soil pH of 4.5 to 5.5, while most Bay Area soils are 7 or higher. This means that you may want to acidify your soil. To really know what you are working with, have your soil tested by a reputable lab. Over-the-counter test kits and strips are unreliable. Unless you want to spend hundreds of dollars on lab equipment, lab tests are really the only way to go. If it ends up that acidification is needed, try amending the soil with coffee grounds, citrus rinds, or oak leaves. You can also buy commercially available acidifiers. Keep in mind that changing pH is a slow process and that it requires regular monitoring.
Blueberry pests and diseases
Citrus thrips, katydids, light brown apple moth, masked chafer, blueberry bud mites, cranberry weevils, scale insects, Pacific flathead borer, plum curculio, sharp nosed leafhoppers, spotted wing drosophila, span worms, and Asian longhorn beetles will all try attacking your blueberry plants, but birds will probably cause the most damage. Personally, I built cage frames around my blueberry bushes and stapled netting to the frame. It works very nicely. Common blueberry diseases include twig blight, canker, stem blight, mummy berry, anthracnose, and blueberry stunt disease. Removing dead or diseased canes and treating with dormant oil can go a long way toward protecting your blueberry plants.
Your blueberry plants can live for 20 years, producing fruit after the third year.
Did you know that the fruit of a pomegranate tree is a berry? That’s if you ask a botanist. Like other berry plants, pomegranates (Punica granatum) have spiny branches and delicious fruit.
When I was a child, growing up in the San Fernando Valley, there was an empty lot down the street. On that lot was a giant old pomegranate tree. It had grown up and out and down, almost like a willow, creating a magical circular space underneath. No one could see us from outside the tree, the growth was so thick! We would pick sun-ripened pomegranates from the outside of the tree and then enter our Secret Clubhouse, where we would tell stories and make wild guesses about growing up, as we munched on the sweet-tart fruity seeds. These healthful fruits are perfectly suited to growing in our drought-prone area. With a small initial investment of time, money, and water, your family can enjoy fresh pomegranates for many years to come.
Before you buy a pomegranate tree, be sure that the variety you are buying is an edible and not an ornamental. There’s no sense dedicating space and water to an inedible variety when you can have an edible! Pomegranates grow in a variety of colors and sizes. Rinds can be red, yellow, pink, orange, green, and even black. Some varieties have seeds that are very hard, while others are softer. The most popular cultivars in California are ‘Wonderful’, ‘Granada’, and ‘Foothill’. The later two are early season varieties. UC Davis offers a helpful Pomegranate Cultivar Chart to help you select the best variety for you and your family. Pomegranates can either be ornamental or edible. Both types can be self-pollinating or cross-pollinated by hummingbirds and insects. It takes a pollinated flower up to 7 months to produce an edible fruit.
How to grow pomegranates
Pomegranates are a very tolerant plant, when it comes to soil types and irrigation. They prefer full sun and hot summers, but they can handle some partial shade. Pomegranates will founder in wet soil or full shade, so choose your site accordingly. Pomegranates can be grown from seeds, but it will take a few years before you get any fruit, and pomegranate seeds do not always grow true to the parent plant. You can also plant rooted cuttings or bare root trees. Grafting does not work for pomegranates. Newly planted trees should be watered every day until new growth is seen. Then water only once a week (assuming it doesn’t rain). Keep weeds away with mulch, just be sure the mulch stays 6 to 8 inches away from your pomegranate.
Pomegranates are deciduous trees that can grow up 30 feet in height and 15 feet wide (most are 6 to 12 feet tall). Pomegranates produce fruit on second-year wood, so you will want to make sure that you leave some of the last year’s growth when pruning. Pomegranates can be pruned as full-sized trees, hedges, landscape anchors, or shrubs. They can also be grown in containers. You can even create bonsai and topiary from pomegranate!
Pomegranate pests & diseases
Like tomatoes and citrus, pomegranates are susceptible to citrus fruit split. Other diseases that can turn up include Alternaria rot, Armillaria root rot, Botrytis blight, and other fungal diseases, especially if plants are over-watered. Common pests include whiteflies, fruit flies, ants, mealybugs, soft scales, leaf-footed bugs, and the pomegranate butterfly.
Eating a pomegranate
Those little seeds are tasty, but getting to them can be a pain. The easiest way I have found is to cut the fruit in half, hold one half peel side up, over a bowl, and beat the bejeezus out of it with a wooden spoon. The seeds fall out and the rest of it tends to stay put. It is easy to remove any other debris simply by adding water to the bowl: the fruit sinks and everything else rises. Viola!
Pomegranates grace holiday tables, a symbol of prosperity, but you can add them to your yard or balcony for some prosperity of your own!
Nothing compares with the sun-warmed sweetness of a raspberry freshly plucked and popped into your mouth. Mine aren't ready yet, but they will be soon!
Raspberries do not ship well, so the specimens we find at the grocery store, like most tomatoes, are simply not up to par with fresh from the garden varieties. The nice thing about raspberries is that that can grow in some unusual places. When I first moved into our San Jose home, I wasn’t sure where I wanted my container raspberries to end up, so I heeled them in (laid them down on the ground and covered the roots with some soil) in the unlikeliest of places - a 6 inch strip of soil next to a concrete slab, where the property line fence was installed. And then I forgot all about them.
Six months or so later, after unpacking, settling in, and beginning to work the garden and landscape, I came around the corner of my house and BAM! There, in the shade of my garage, the neglected raspberries had thrived and were climbing the fence! All in a 6 inch strip of what was probably construction soil.
What made that dubious location work was afternoon shade and a ready supply of water. It was winter in the Bay area and a rain gutter downspout pointed directly their way. You may not want to try growing your berries in such a questionable location, but it sure shows how tenacious these cane fruits can be. Once the plants are established, they can produce fruit for decades. In addition of the traditional red raspberry, you can also find cultivars that are golden, purple, and black.
How to grow raspberries
Raspberries love water. Sunburn is a common sign that your raspberries are not getting enough water. Our raspberries get nearly daily waterings from the bucket of water we collect in the shower as we wait for the water to heat up, at least when it’s not raining. At the same time, our heavy clay soil can also lead to drowning if there is too much water. Since raspberries have relatively shallow roots, regular light watering is better than less frequent deep watering.
Raspberries prefer cooler, damp weather, but you can recreate those conditions by adding them to a shade garden or growing them in containers under a pergola or on a shady balcony. The plants need lots of sun but they prefer a little shade in the heat of the afternoon. Raspberries grow best in soil with a pH of 5.5 to 7.0. They love raised beds and fence lines provide the perfect medium for trellising. If the cane tips reach the ground, rather than producing fruit, new roots will form, so trellising is a good idea. That’s how bramble fruits spread in the wild. They also spread using underground stems called stolons.
While you can start raspberries from seed, it is much more satisfying to start with cuttings, dormant bare-root plants, or potted seedlings. Ideally, you will remove any damaged roots or stems before planting your raspberries in a shallow hole, making sure that the crown is slightly above soil level. Spreading the root mass out, covering with soil, and patting it down to eliminate air pockets will help your plants get a good start in their new location. Be sure to water well, to help the soil settle. Plants should be placed 2 to 3 feet apart and new plants should be trimmed down to be only 6 inches tall, to encourage strong root growth. Black and purple raspberries should be spaced 3 to 4 feet apart.
Raspberry plants have perennial roots and crowns that grow new canes each year. These new green canes are called primocanes. Then they turn brown and go dormant over the winter, to one degree or another. In spring, these now 2-year old canes are called floricanes. Flowers and fruit are only produced on floricanes, so you don’t want to prune them out.
Fruit production varies between everbearing and summer-bearing varieties. Summer-bearing raspberries bear one crop in summer on two-year old canes, while everbearing cultivars have two crops, one small crop in summer on new canes and one heavier crop in fall on two-year old canes. Everbearing cultivars are sometimes called fall-bearing. It is a good idea to check with your local Cooperative Extension Office to find the best cultivar for your location.
How to prune raspberries
Raspberry pruning methods will vary, depending on the cultivar. Fruit-producing canes of summer-bearing red and yellow raspberries should be cut to ground level after harvest and removed. Thin primocanes to no more than 4 or 5 per foot. Fall-bearing raspberries can be treated the same as everbearing varieties, if you want both the summer and fall crops. Otherwise, leave the canes in place for an extra year. If you are growing black or purple raspberries, you will need to pinch the canes when they reach 2 to 2-1/2 feet in height and then again two or three times during the summer. This will promote lateral cane growth for more fruit. Be sure to remove any dead or damaged canes whenever you are working your bramble fruits. Canes left to grow a third year may produce some fruit on the lower part of the canes but they should be pruned out after that to make room for new canes and to reduce the spread of disease.
Raspberries pests & diseases
Raspberry pests include borers, spider mites, aphids, and Fuller Rose Beetles. Fungal diseases and raspberry leaf curl can also be a problem. Healthy plants are far less likely to be vulnerable, so you will want to feed your raspberry plants each time they start a new bloom cycle. According to UC Davis, 3 to 6 pounds of blood meal, feather meal, or fish meal should be applied for every 100 feet of row. Most of us don’t have a 100 feet row of raspberry plants, so I did the math and it works out to approximately 1 to 2 ounces per plant.
Raspberries are self-fertile, which means you can get fruit from a single plant. If you really love raspberries, and have the room, you can grow a raspberry hedge as part of your edible landscape!
Note: If you have never grown raspberries before, you may be surprised to learn that they ripen unevenly. One part of a berry will look ripe days before the rest of it does. This is okay, simply wait (if you can!) for the entire berry to ripen before picking.
Everyone knows what berries are, right?
Sweet, juicy summer favorites commonly include strawberries, blueberries, raspberries, and blackberries. Of course, in the world of botany, you'd be wrong on most counts.
What are berries?
Botanically, berries are the fruit (pericarp) produced by a single ovary. By this definition, the following plants are all berries:
Berries that are not berries
Strawberries and raspberries are not berries. Weird, right? Strawberries are accessory fruits. The flesh of an accessory fruit is not made from the ovary. Instead, it is a protective growth from surrounding tissue. Raspberries and blackberries are aggregate fruits. Aggregate fruits are made from single flowers, but many ovaries that are held together in a cluster. Speaking of clusters, what about grapes? Yep, grapes are, by definition, berries.
Plants that produce berries are called baccate or bacciferous. [I wonder if that name comes from Bacchus, the Roman god of wine.] Most berries are sweet and delicious, but not all of them. Potato flowers produce berries, but don’t eat them - they’re poisonous! Elderberries and mulberries are fine to eat when ripe, but poisonous when unripe. People have been eating berries for as long as we have existed, but we’ve only been cultivating them for a few hundred years, so there’s probably a lot more to learn.
Berry plant basics
Generally speaking, nearly all berries are shallow-rooted plants that prefer southern or western exposure. They do best in loose soil, so you can help berry plants by working a lot of compost into our heavy clay before planting, especially for blueberries. Soil compaction will seriously interfere with berry production. The use of deep-rooted cover crops, such as hairy vetch, mustard, fava beans, marigolds, or rye will loosen the soil, add nutrients, and reduce erosion in berry plantings.
Berries do well in raised beds and they prefer soil with a pH of 6.2-6.8 (slightly acidic). Our soil tends to be more alkaline, and our water supply is very alkaline, so regular treatments may be necessary. Over-the-counter pH tests are only marginally useful. I urge you to get your soil tested regularly by a lab.
Berry pests and diseases
While each species has its own particular problems, most berries are susceptible to verticillium wilt and other fungal diseases. Crops should be rotated every 5 years to interrupt the pathogens’ life cycle. Commercial berry growers regularly fumigate with methyl bromide to combat black root rot. Methyl bromide is an ozone-depleting chemical that has been phased out of use in most other countries. You can help harvested berries last 30% longer by storing them in the refrigerator and only washing them just before eating.
People started cultivating strawberries commercially in the late 18th century. The Romans thought its wild cousin had medicinal uses due to the heart-shaped berry. Strawberries require an accumulation of 200-300 hours of temperatures between 32-50 °F to break dormancy. These are called chill hours. Strawberry flowers look hermaphroditic but they function as either male or female. New plants can be propagated using runners. If you want fruit, remove the runners. Like potatoes, strawberries are especially well suited to planting in towers. Powdery mildew, leaf spot, and leaf blight are common diseases, and pests include ants, fruit flies, slugs, moths, thrips, weevils, mites, and aphids.
Did you know that blueberries were not domesticated until 1911? Unlike strawberries, most blueberry varieties need 650-850 chill hours. What this means in our area is, if we have an extremely mild winter, blueberry bushes may not know what to do with themselves. Blueberries love acidic soil. They perform best in soil with a pH of 4.2-4.8! You can acidify soil by adding sulphur. Be sure to follow package directions when adding sulphur. According to researchers at Cornell University, nitrate-based fertilizers can be toxic to blueberries.
Blackberries and raspberries are close cousins. Due to color variations, sometimes the only way to tell the difference is to pick them. If the torus (receptacle stem) stays with the fruit, it’s a raspberry, if it separates from the fruit, it’s a blackberry. Both varieties are called bramble fruits or caneberries, because the fruit is produced on bristly canes each year. First year canes (primocanes) produce palmately compound leaves and no flowers. Second year canes (floricanes) do not get longer. Instead, they produce lateral buds with 3-5 leaflets. At the ends of these lateral buds, fruit is produced on short stems called racemes. These members of the Rubus genus don’t seem to care what type of soil they are in. The most common problem with Rubus plants is insufficient pollination. You can improve the odds of pollination by installing plants that attract pollinators. Keep in mind, every time the tip of a cane reaches the ground, a new plant will start to grow, so it is important to trellis these berries, unless you want an impenetrable bramble patch! Birds, caterpillars, aphids, weevils and beetles are the biggest pests. Anthracnose cankers can be treated with Bordeaux mixture (lime, water and copper sulfate). Raspberries should not be planted where peppers, eggplants, tomatoes, bulbs or potatoes have been grown. These plants are often hosts for verticillium wilt, which can stay in the soil for many years. Traditional folklore says you should not harvest blackberries after Old Michaelmas Day (October 11th), because the devil has spit on them. Though it sounds funny, the truth behind the fiction is that cooler wet weather can cause certain molds to start growing on the fruit and may make it toxic. Once established, blackberries and raspberries will come back, year after year.
Last summer, I installed three young currant seedlings. They do well in our area and the fruit is delicious, but the summer heat really took a toll. There are three basic varieties of edible currants: blackcurrant, redcurrant, and white currant. They are, along with gooseberries, members of the Ribes genus. Despite the name, these fruits are not related to the dried currants used in baking; those are a type of grape. If you want to grow currant berries, you can’t live in New Hampshire, North Carolina, or West Virginia. If you live in Massachusetts, New Jersey, Rhode Island or Delaware, you’ll need a permit. These bans are in place because Ribes can carry White Pine Blister, an imported Asian rust fungus that has devastated high elevation pine forests. Currants generally prefer cool, well-drained soil, in partial shade or full sun. In our warmer climate, they prefer heavy soil (yay!) and partial shade. They can be grown as either shrubs or trees. Fruit is borne on spurs of 2- and 3-year old wood. Pests include aphids, spider mites, imported currantworms, and currant borers. Currants need a lot of potassium, but they are sensitive to potassium chloride, a common ingredient in fertilizer.
Whether or not it’s technically a berry, you can add these plants to your garden or foodscape for many years of delicious fresh food.
Have you ever seen strawberries with leaves growing out of the fruit? This is called vivipary.
Vivipary, also known as phyllody, describes a condition that occurs when the embryo within the seed breaks through the seed coat while still attached to the parent plant. Viviparity mean “giving live birth’. Now, viviparity is completely normal in mammals, but it looks really strange when strawberries do it!
When strawberries begin to exhibit vivipary, the tiny black seeds on the surface, called achenes, are actually sprouting leaves!
These fuzzy strawberries are still edible, but the tiny leaves don’t taste very good. After showing it to all your friends and neighbors, you could try planting the viviparous strawberry, but you wouldn’t have any luck. Strawberry seeds that develop viviparously generally do not develop any roots.
Vivipary in strawberries is rare. While vivipary in other plants can be caused by phytoplasms (bacteria-like parasites carried by leafhoppers), physiological damage is the culprit in strawberries. This damage occurs in runners held in cold storage or subject to freezing temperatures during the winter.
So, protect your strawberry plants in winter and enjoy those luscious fruit in summer without tiny leaves attached!
Plant blackberries and dark, juicy berries will be your reward for many years to come! Excellent on cereal, as jam or jelly, in a cobbler, or used to make wine, blackberries are an excellent addition to any garden.
Blackberries grow from a perennial root system, putting out new biennial stems (canes) each year. In a blackberry cane’s first year, when it is called a primocane, it will reach it’s full length without producing fruit. In it’s second year, it becomes a fruit producing floricane. The fruit is produced on racemes found at the tip of lateral buds. After the second year, the cane dies, making room for the next year’s crop. Botanically speaking, blackberries are not berries at all. Like raspberries, they are an aggregate fruit made up of small drupelets.
First and second year canes are often covered with numerous sharp prickles, mistakenly called thorns. Prickle-free (thornless) varieties are available. I have heard from several growers that thornless varieties produce bigger fruit, but that varieties with prickles have far better flavor. Personally, I’ll take quality over quantity any day!
There are two basic cultivars of blackberries: erect and trailing. Erect blackberries have stiff canes that arch. While not completely self-supporting, erect blackberries tend to grow into huge thickets if not pruned. Trailing cultivars, also known as dewberries, will spread horizontally across the ground. If you live in a cold area, there are even late-season blackberry varieties that can produce late summer crops. The University of California provides an excellent list of blackberry cultivars.
How to grow blackberries
Blackberries are rugged. In the wild, they grow best near creeks, in alluvial soil. Blackberries can be grown in containers, as long as they are at least 5 gallons in size. Blackberries can be grown in poor soil and will transform an empty lot into a fruit-producing thicket, left unchecked. Blackberries do best in raised beds where drainage and weeds are more easily controlled. To plant your blackberries, follow these tips for the best results:
Pollination is critical for fruit production. If blackberries are being grown indoors, hand-pollination will be needed. To hand-pollinate, simply take a fine paintbrush or Q-tip and touch each flower repeatedly every day until the flower begins to turn brown. To protect your outdoor pollinators and other beneficial insects, avoid using chemical pesticides during bloom.
Blackberry pruning & training
Like other cane berries, blackberries are very low-maintenance once established. After a cane has produced fruit, it can be removed. This cuts down on the thicket effect and it encourages the root system to generate new canes that will produce even more fruit.
First-year canes can be pruned to a manageable size or trained onto a trellis. It is a good idea to wear long sleeves, long pants, and heavy gloves when working with blackberries. Those prickles are sharp!
Blackberries are green when they are red. This old saying reminds blackberry growers that unripe blackberries are red. They become ripe 2-3 weeks later, when the fruits are black, but still firm. Do you know how to tell blackberries and raspberries apart? Hint: It’s not the color. The only way to really tell the difference between blackberries and raspberries is to look at the way the fruit comes away from the torus, or stem. If the torus comes with the fruit, it is a blackberry. If the torus breaks away from the fruit, it is a raspberry.
British folklore warns against picking blackberries after Old Michaelmas Day (Ocober 11) because the devil is said to have spit on them! This tradition has a reasonable explanation in science. As cooler, moist weather kicks in, several types of mold can begin to grow on the fruit which can make it toxic. So, enjoy your blackberries before October 11th and leave the rest for the birds!
Blackberry pests & diseases
As rugged as blackberries are, there are still some pests and diseases to watch for. Deer, birds, and other critters will try to enjoy your harvest before you do. Netting can help, but it’s a pain to take off. Many varieties of caterpillar will also happily munch on fruit and leaves, so monitor plants every few days in spring and hand pick those beasties. You can always feed them to your chickens!
Being close cousin to raspberries, blackberries are prone to many of the same pests and diseases. In either case, watch for signs of these blackberry (and raspberry) pests:
Blackberries may also be infected with the following diseases:
Now, don’t let all those threats to your blackberry crop discourage you from trying this amazing plant. They are only possibilities and blackberries seem to survive against the odds. Even notorious Brown Thumbs have been able to grow blackberries successfully! You can, too!
Mites are tiny spiders that suck the living juices from nearly a thousand different garden plants. Being closely related to ticks, some varieties of mites also suck blood from mammals, like us! The study of mites and ticks is called acarology.
Mites prefer soil that is high in organic content with plenty of moisture. Unfortunately, that describes nearly all of our container plants and many of the microclimates found in Bay Area gardens. A highly adaptable critter, there are over 42,000 species of mites worldwide. Aside from nest mites, dust mites, varroa mites, and many others that attack birds, animals, and bees, respectively, common garden mites include gall mites, spider mites, and thread-footed mites.
Spider mites get their name because they build protective webs around eggs and feeding areas. The most common spider mites in the Bay Area are the two-spotted spider mite, the strawberry spider mite and the Pacific spider mite. They are often found on the underside of leaves, where they pierce plant cells to feed. These mites are very small, usually less than 1 mm (0.04”) long, so they are all too easy to overlook until the damage becomes significant. It doesn’t take long for a population to develop, either. A single female can lay 20 eggs a day and live for up to 4 weeks. Since each offspring hatches within 3 days and becomes sexually active in only 5 days, a single, fertilized female and her offspring can produce millions of spider mites in a single season!
An interesting note: female spider mites have two sets of chromosomes, like we do, but males only have one. If an egg is fertilized, it will hatch female. If it is not fertilized, it will hatch as a male. Also, female spider mites are able to “decide” whether to lay male or female eggs, depending upon environmental conditions. To control spider mites, insecticidal soap is your best bet. Neem oil, diluted and combined with a surfactant (dish soap) can help. If chemical pesticides are used, repeated applications will be necessary (and progressively ineffective, as mites can develop resistance).
Most thread-footed mites, also known as white mites, feed on fungi and algae, a few varieties have evolved to attack leaves. Specifically, the cyclamen mite and the broad mite are able to inject toxins that thin the cell walls of mature leaves. Damaged leaves display puckering, twisting and stunting.
The only known effective chemical pesticides against mite infestations are endosulfan, dicol, and ethyl bromide fumigation. Endosulfan was globally banned due to its toxicity to humans and its ability to accumulate in an environment, dicol is considered a “moderately hazardous” pesticide, closely related to DDT, and the state of California classified ethyl bromide as carcinogenic and a reproductive toxin - not anything you want to be spraying on food plants. Broad spectrum pesticides do more harm than good because they also kill beneficial insects that feed on mites. You can buy predatory mites that help control mite infestations. If an infestation is discovered, sprays of water, insecticidal oils (neem, cottonseed or canola) soaps can be used to displace mites and make life harder for them. Garlic extract and oil of clove, rosemary, cinnamon, mint and others can also be effective. These natural treatments can be dangerous to plants, however, so use them carefully. The same goes for sulfur, especially on cucurbits. Observation and prevention are far easier than eradication.
One of the easiest ways to avoid mite infestations is to create a quarantine area for new plants. This protects established plants from new infestations and gives you the time needed to see if a new plant is carrying any pests or diseases. Also, proper irrigation reduces water stress in established plants, making them better able to protect themselves. Mites prefer dusty conditions, so keeping garden paths, trees, shrubs and other areas clean can significantly discourage mites. Encouraging beneficial insects, such as lady beetles, lacewing, and pirate bugs, by providing water and habitat, can significantly reduce mite populations without the use of pesticides or sprays.
Fireblight, or fire blight, is a bacterial disease that frequently attacks trees in the pome family. This includes pears, quince, crabapple and my apple tree! Fireblight can also attack raspberries and blackberries, so you know I don’t like it!
The Erwinia amylovora bacterium is the cause of fireblight, but you’ll never see it without a microscope. The most common first sign of infection is the die-off of an entire twig. The dead leaves hold fast to the stem throughout the growing season as the infection spreads.
Fireblight can be fatal to your fruit trees and it is difficult to manage. Carefully monitoring your trees when they flower can provide early warning. Fireblight normally attacks through the blossoms, carried in by bees and other insects from other infected trees. As blossoms become infected, they wilt and turn dark brown. The infection then spreads down the twig. Very often, the tip of the diseased twig will curl into a shepherd’s crook shape.
Insects pick up the bacteria from small, insignificant looking cankers that become active in spring. These cankers are actually dead tissue from the previous year’s infection. A clear, tan ooze can be seen dripping from these cankers. Each droplet can contain millions of bacteria which are then spread by insects and droplets of water. Infestation can be prevented with applications of Bordeaux mixture in fall and winter.
Once identified, the only treatment is removal of the diseased tissue. Cuts should be made 8-12” below the infected area and clippers should be dipped in 10% bleach solution after each cut to prevent further spread. The infection can be seen by scraping off the bark and cambium layer to expose pink to orangish-red streaks. It is critical that all of the infected tissue is removed or the disease will continue to spread.
I discovered a new bug while pulling weeds under one of my apricot trees this morning.
It is 1/4" long, somewhat flattened, and it has a distinct light green triangle on its back. After a little research, I learned that it is called a Lygus bug.
You can grow a surprising amount of food in your own yard. Ask me how!