Ribes pests and diseases

Aphids, brown marmorated stinkbugs, clearwing moth larvae, currant borers, gooseberry fruitworms, gooseberry sawflies (Nematus ribesii), also known as currant sawflies, mites, imported currantworms, and the larva of some moths and butterflies are common Ribes pests. And birds.


Problems are more commonly caused by mineral imbalances in the soil or improper irrigation. These plants are susceptible to several fungal diseases, such as American gooseberry mildew, anthracnose, currant cane blight, gray mold, leaf spot, powdery mildew, rust, and septoria leaf spot. Avoid overhead watering and be sure to provide good drainage.


Ribes grow best in cool, moist surroundings with good drainage, but partial shade and regular irrigation make them possible elsewhere. These plants can be grown in containers and are self-pollinating. Ribes take well to regular pruning, making them excellent patio or balcony plants, and renewal pruning each winter keeps them healthy and productive.


Ribes berries are delicious and their flowers provide nectar and pollen to a wide variety of butterflies.

The mallow family (Malvaceae) is a mixed bunch. It contains several weeds and some favorite crops. It also includes several ornamentals, such as hibiscus, hollyhocks, and linden trees. Scientists are still arguing over the specifics of the mallow family, but let’s see how it applies to gardening.

Mallow pests and diseases

Weedy members of the mallow family can carry several diseases, including rusts, tomato yellow leaf curl, and tomato spotted wilt. Members of the mallow family are also susceptible to bacterial leaf spot, gray mold, and phytophthora blight. Aphids and spider mites are the most common pests.


If you grow hollyhocks and okra, you may want to keep them at a distance from each other, to prevent the spread of disease.


​Finally, the marshmallow plant (Althaea officinalis), a native herb of Europe, is a member of this family and its roots were used to make marshmallows some 4,000 years ago in Ancient Egypt. Today, marshmallows are made out of sugar and gelatin.

Many people consider amaranth, buckwheat, and quinoa to be cereal grains, but they are not. Instead, these are all broadleaf (dicot/eudicot) plants known as pseudocereals. Other seeds that are not grains include lentils, peas, and other legumes. And that “recreational/medicinal” grass? It’s not a member of this family either.


Grass family pests and diseases

Grains and grasses are prone to fungal diseases, such as leaf scald, leaf spot, net blotch, stripe rust, and stem rust. Along with grasshoppers and crickets, and other common pests, this family battles crane flies, stinkbugs, and wireworms. Also, aphids may carry a viral disease called barley yellow dwarf.


Your average lawn grass has a root system that only goes down a few inches. Other grass plants have roots that can go down 5-10’ or more. So, how about making a little room for a patch of grain? As a food crop, I expect that it will be much like endive, nasturtiums, lentils, and tomatoes—it will continue to turn up long after I have stopped planting it.


The grain and grass family provides 51% of all human dietary energy. How much space does it get in your garden?

• black cutworms (Agrotis ipsilon)
• greater wax moths (Galleria mellonela)
• Japanese beetles (Popillia japonica)
• long-tailed skippers/bean leafroller caterpillars (Urbanus proteus)
• Mexican bean beetles (Epilachna varivestis)
• southern green stink bugs (Nezara viridula)
• tobacco budworms (Heliothis virescens)

 
There are four predatory stink bugs found in the U.S., mostly in southern states.


Anchor stink bugs

Anchor stink bugs (Stiretrus anchorago) are from Central and North America. They occur in several different color variations, ranging from black, white, and tan, to orange or red and black, to green and yellow.

As you search your garden for stink bugs, with a bucket of soapy water in hand, keep in mind that not all of them are bad. Sorting between beneficial and pest stink bugs is made a little easier because many predators tend to be more brightly colored and patterned.


Which types of stink bugs have you seen?

Similar to ladybugs, red-shouldered stink bugs are notorious for invading homes in autumn. And don’t try vacuuming them up or your vacuum will stink. Instead, invert a plastic bag over your hand, pick those little suckers up, and drop them into a container of soapy water. The same method works outside in the garden, as well.


Stink bugs can smell pretty bad. Even my hens turn up their beaks when one crawls by, so it’s up to you!

Say stink bug damage

Despite their fascinating wardrobe changes, Say stink bugs are much like other stink bugs. They emerge from leaf litter and ground cover in early spring, feeding on mallow, mustards, Russian thistle, and other favored weeds until your garden starts happening. They then move in, feeding on all those seeds you just planted. They especially like members of the grass family, which means alfalfa, barley, corn, millet, oats, rye, and wheat are all at risk, as well as your lawn. Then they go after your beets and tomatoes. Especially tomatoes.


Using piercing mouthparts to suck the juices from your plants, Say stink bugs may also introduce yeasts that cause fruits to rot.

As with other stink bugs, the best control methods are being alert and handpicking. If you drop stinkbugs into a container of soapy water, the smell isn’t a problem.

Are damaged areas on tomatoes due to dehydration, deficiency, or disease? Is it blossom end rot, sunscald, or buckeye rot? And what can you do about it?

If there isn’t enough water available to move the calcium to where it is needed, cell walls surrounding the blossom end of the fruit will collapse, creating a uniformly dark brown or black area ONLY on the lower sidewall or blossom end of the fruit. If you see blossom end rot, irrigate more heavily and more often.

​
​If the damaged area is lighter in color and higher up the side of your fruit, it may be sunscald.

Buckeye rot symptoms

Buckeye rot is a disease caused by three different types of Phytophthora: P. capsici, P. drechsleri, and P. nicotiana var. parasitica. Phytophthoras are water molds (oomycetes) responsible for several plant diseases. This disease is common in the southeast and south-central regions of the United States but has been found elsewhere. It occurs most often after extended periods of warm, wet weather with temperatures ranging from 75°F to 86°F. Buckeye rot can infect tomatoes, peppers, and eggplant, as well as pineapples, potatoes, and tobacco.


​At first, all you may see are smooth, grayish-green water-soaked spots. Damping-off and stem cankers may also appear. As the disease progresses, those lesions turn into the classic bull’s eye pattern of large, concentric rings, alternating between light and dark brown. The edges of these lesions will be smooth but not clearly marked. Eventually, white fungal growth can be seen on the lesions.


Other diseases that may exhibit similar symptoms include anthracnose, cucumber mosaic virus (CMV), and late blight. In each case, some differences can help you diagnose the problem:

• anthracnose – irregular lesions on leaves, as well as fruit
• cucumber mosaic – downward leaf cupping and deformed midribs
• late blight – lesions are rough and raised and leaves are also affected

Buckeye rot management

Starting with healthy, disease-free seeds and plants is the first step toward preventing nearly all plant diseases. Since buckeye rot spores can travel on seeds, transplants, clothing, and garden tools, it’s a good idea to keep things clean. Spores can also be splashed onto healthy plants by rain and overhead watering, so use soaker hoses or water at ground level and allow the soil surface to dry out between waterings. Mulching around plants can reduce the splash effect, as well as reduce weeds and evaporation.


You can reduce the chance of many fungal diseases by providing good drainage and reducing soil compaction. Since buckeye rot spores are found in soil, the disease is most likely to affect fruits closer to the ground. If you keep fruit up high with stock panels, tomato cages, or trellising, you can reduce the likelihood of buckeye rot occurring. Three-year crop rotations are also believed to help prevent buckeye rot.


​Now you know.

What is rock dust?

The contents of your rock rust shipment will depend entirely on where it was mined. It may contain a lot of calcium. Or none. The same is true for other minerals. That being said, on average, rock dust contains significant amounts of aluminum, silicon, and sometimes iron. It may also contain copper, magnesium, manganese, potassium, sulfur, and zinc. But does your soil need these elements? Without a lab-based soil test, you really can’t be sure.


Your rock dust may also contain toxic levels of aluminum, arsenic, cadmium, chromium, copper, lead, nickel, and sodium. Believe me when I tell you that dealing with toxic levels of nutrients is a lot harder and takes a lot longer than adding missing nutrients. I’m speaking from experience. If you do nothing else for your garden this spring, get your soil tested before you add anything.


Big batch or specific sediments?

If your soil is low on a certain nutrient, rather than relying on luck, you can order specific types of rock dust. If you know your soil is low in something, you can apply crushed versions of that nutrient in the form of rock dust. Of course, it costs more that way. The nice thing is, it is an organic method of fertilizing your plants.


Making rock dust work for you

If you decide to apply rock dust, combining it with nutrient-rich organic matter, such as aged compost or manure, creates a slightly acidic environment more likely to break down the dust into bits small enough to be carried by irrigation water into your plants.


What rock dust is not

Because it does not contain significant levels of nitrogen, phosphorus, or potassium, rock dust is not a fertilizer.


Bottom line, in my opinion, rock dust is best left to commercial growers who regularly deplete their soils through heavy use and often have a fleet of chemists, soil experts, and lab technicians on hand to determine what’s needed and what’s in each particular load of rock dust.

Butt rot? Really?


Yes, Virginia, there is a fungal disease of almond trees called butt rot. Is full name is Ganoderma root and butt rot and it can kill your tree.

Fusicoccin, or constriction canker, is a fungal disease of almonds and peaches.


You may find this word easier to say than to read at first. It is pronounced FUSE-ih-koksin. Once you say it aloud a few times, it doesn’t feel nearly as intimidating. [Unfortunately, I couldn’t find a few image, but I have a request in the works.]


When I first found this word, the disease was not present in California. Now it is. These things keep moving forward which is why we need to keep learning.


Fusicoccin is a disease that forces plants to open their stoma. Stomata are tiny breathing holes found most often on the underside of leaves, but also on stems and other tissues. Plants use stomata to create bubbles of high humidity which then evaporate, pulling moisture up a plant’s vascular system. This is how plants pull water from the ground and it’s pretty amazing when it works the way it should. When stomata stay open, plants start drying out.


Disease progression

This disease is caused by the Fusicoccum amygdali fungi, which is found throughout the United States, Argentina, China, Spain, Italy, and Hungary.  These fungi produce chemicals that acidify plant cell walls, causing stoma to open permanently. They enter plants through leaf scars and stipules in the fall and bud scars, blossoms, and fruit scars in spring. Basically, any place there is a fresh opening.


Fusicoccin symptoms

The first sign of fusicoccin is wilted leaves and shoots, followed by long, brown cankers on infected buds and nodes. These symptoms are usually seen in early summer and become worse as the disease progresses. You may see constructed areas at the base of infected shoots. Gum may be seen oozing from infected areas, but don’t use that as a diagnostic tool since gumming is a common response to several diseases and disorders. Fruit on infected stems tends to shrivel up and fall to the ground, further spreading the disease.


Managing fusicoccin

Research has shown that certain fungicides can control this disease. But many of these products can cause birth defects, cancer, and infertility. Not exactly what you want around your tomatoes and basil!


Another option is to fight fire with fire. Or, in this case, fight fungi with fungi. Trichoderma harzianum and Trichoderma viride are antagonistic fungi that work as biofungicides, parasitizing fusicoccin pathogens. Of course, they will also damage your homegrown mushrooms. As gardeners, we must choose our battles. You can buy these biofungicides online or from your local garden center.


In the case of fusicoccin, prevention involves keeping trees healthy in the first place, applying biofungicides according to package directions, and buying resistant varieties whenever possible. If fusicoccin appears on your peach or almond trees, remove infected branches by cutting several inches below the affected area and throwing those twigs in the garbage.

Golden pearls look like tiny tomatoes or yellow currants, but they taste more like cherries and can make you very sick if you eat them before they ripen.


Native to Africa and Europe, golden pearls (Solanum villosum) are now found in Australia and North America. Also known as golden wonderberry, hairy nightshade, red nightshade, and woolly nightshade, this sprawling annual is considered a weed by many.

Plant choice

If you grow apples or cherries, beans or beets, blueberries, broccoli, cabbage, cauliflower, pumpkins, spinach, well, if you have a garden and there are deer in the neighborhood, there’s going to be a problem. Deer will always go for arborvitae, azaleas, hardy geraniums, hosta, rhododendrons, roses, and tulips. There are some plants, however, that deer don’t eat.


By installing plants that deer are unlikely to eat throughout the landscape, deer should be less likely to cause significant damage. These plants include most herbs, mint and lemon balm, members of the onion family, artichokes, asparagus, eggplant, fennel, figs, lavender, and rhubarb. They also seem to avoid plants with fuzzy leaves, such as lambs ear or yarrow, prickly plants, and plants toxic to deer. That list includes bleeding hearts, daffodils, false indigo, hellebores, monkshood, poppies, and spurges.


There are also plants that deer would rather not eat, but will if they are particularly hungry. This group includes tomatoes, peppers, and potatoes, squash, cucumber, Brussels sprouts, cilantro, horseradish, okra, melons, and chard. Keep in mind that tender, young shoots of nearly every plant are considered fair game by deer, and deer do not read reports or studies, or blog posts about what they do and do not eat. If your local deer love artichokes and horseradish, you’ll have to figure out ways to protect them. [Rutgers University offers an extensive list of what deer do and do not generally eat.]


Scare tactics

Deer spook easily, so sudden noises and movements can make them turn and run. You can use plastic bags tied to the tops of poles, old CDs hanging in trees, pinwheels, or windchimes. Like scarecrows, scare tactics lose their effectiveness over time. Commercial growers use air cannons but your neighbors probably wouldn’t appreciate that one.


Garden hoses attached to motion-detectors are said to be effective. I can’t help but picture a herd of deer lounging on my lawn, nibbling garden treats and enjoying the cool spray, like a bunch of kids playing in the sprinklers on summer vacation. I could be wrong. I had a neighbor, many years ago, who entertained the neighborhood children each Halloween with well-thought-out theatrics, which often included a leaf-blower attached to a motion detector. It just might work to protect your garden plants, too.


The big stink

Deer rely heavily on their sense of smell and they avoid areas frequented by predators. If they smell predators, they will generally go down a different path. You can find countless recipes online for DIY deer repellants. I have no idea how well any of them work, and some of them sound awful. Personally, I have used Bobbex-R with good results. It stinks (to humans) for about 45 minutes, then goes away. Deer, rats, and squirrels tend to avoid it for several weeks. I imagine that other commercially available deer repellants work in much the same way.


Pungent herbs and scented geraniums are known to repel deer, as does cheap perfume sprayed on strips of fabric and zoo poo from the lion’s den. If you have dogs, they can help discourage deer from grazing in your garden. Other tips to reduce deer damage include:

• keep deer favorites closer to your house, or avoid planting them in the first place
• harvest crops as soon as they are ready
• eliminate hiding places
• make your landscape difficult for deer to navigate with varying levels, sunken rain gardens, stacked rocks, and terracing
• do not feed them

And be sure to switch things up. Deer can get used to just about anything, especially if they are hungry. If you move things around and cycle through different deer repelling tactics, they are more likely to be effective.


Tell us your deer story! How do you keep deer out of your garden?

True daddy longlegs are harvestmen, not spiders. They are most closely related to mites. If you were to compare cellar spiders with daddy longlegs, you would see that daddy longlegs have single eyes (or no eyes, depending on the species) and fused, pill-shaped bodies. They also differ in that they do not build webs, do not produce venom, and can eat chunks of food, as well as liquids. They defend themselves using stinky chemicals.


These creatures prefer hiding in moist areas, under logs and rocks, so you may find one under your kitchen sink or in a crawl space or basement.


Daddy longlegs are fascinating. They breathe using tracheae in their legs. And if one of those legs breaks off, as they too often do, it will continue to move because of a pacemaker mechanism found in each femur. This movement may continue for up to an hour. Scientists think this may have evolved to trick predators.


While daddy longlegs are predators in their own right, they get most of their nutrients from decomposing plant and animal matter, and manure. When they do hunt, they ambush their prey. This is impressive because their eyes cannot form images. [Don’t ask me. I have no idea how they do it.]


Daddy longlegs daddies are territorial and often care for the eggs laid by several different females, cleaning the eggs and protecting them from unrelated, egg-eating female daddy longlegs. [And we think our families are complicated!]


So, crane flies are pests, cellar spiders are helpful, and true daddy longlegs are pretty much neutral. Now you know.

As for the risks mentioned earlier, when a stem produces a lot of secondary growth, adventitious buds are often killed off. I have no idea who makes that decision or how it is carried out. I guess plants figure those outliers are expendable, as is often the case.


Which plants in your garden have adventitious buds?

What’s strange about potato mop top is that plants grown from cuttings of infected plants may not show any aboveground symptoms, but they will have even more infected tubers than the parent plant.


Potato mop top management

The potato mop top virus is responsible for crop losses of up to 67% and it is a tough disease to control. There are no resistant varieties. Not yet, anyway, though russet-skinned potatoes seem to be less sensitive to PMTV. And there are no chemical treatments against viruses either.


Commercial growers apply fungicides that contain fluazinam to the soil to control the long-winded amoeba-like creatures mentioned earlier. Fluazinam products are commonly used against late blight, another potato disease.


Good sanitation and vector controls are really your only options when it comes to managing potato mop top. This means insisting on certified disease-free seed potatoes and nothing less.


Plus, you can reduce the occurrence of powdery scab by improving drainage. The easiest way to do this is by mulching with a thick layer of free arborist chips. [My concrete-like clay soil is now loose, dark, and productive, thanks to free wood chips!]


Other practices that help reduce the odds of potato mop top occurring in your garden include avoiding excessive applications of fertilizer that contain nitrate or ammonium nitrogen. These stimulate root growth, providing lots of tender new victims to both diseases. Also, allow the soil to dry out between waterings, especially early in your potatoes’ development. And wait until the soil is warmer to plant in the first place. This helps your potato plants be stronger and healthier from the start. And, as always, be sure to disinfect your garden tools regularly.


If a plant becomes infected with potato mop top, it must be removed and thrown in the trash. What’s worse, you can never grow potatoes in that soil again. Ever.


As spring approaches, I’m watching my potato patch as it starts waking up from its winter sleep. New shoots are beginning to appear and I am monitoring for signs of this and other diseases so I can nip them in the proverbial bud. (Sorry, I couldn’t resist.)

Symptoms of potato virus X

You may not see any symptoms at all, besides a drop in tuber production, and your plants may look bushier than normal. Or, you may see chlorosis, dead spots in tubers, leaf crinkling, mosaic, ringspot, and smaller leaves. [Sadly, I was unable to find any photos I could use.]


Potato virus X management

Potato X disease is not transmitted by insects. It is only spread mechanically, on tools, clothing, and infected roots and tubers. If you avoid walking through infected areas and only use clean, disease-free seed potatoes, you should be able to prevent this disease. Crop rotation can help break the cycle.


Since potato X also appears on weeds in the same family, it’s a good idea to keep bindweed away from your susceptible crops. Heck, it’s always a good idea to keep bindweed out of your garden and landscape.


Some potato varieties, such as Atlantic, HiLite Russet, Norwis, and Sebago, show some resistance to PVX, so you may want to use them in your potato patch.