Bulb mites, also known as spinach crown mites, refer to a small collection of very tiny pests that can damage your onions, garlic, saffron crocus, and spinach plants.
Bulb mite description
Bulb mites are a collection of pests from the Rhizoglyphus and Tyrophagus genus and they look like miniature ticks with spiky hairs. These pests may be tiny, but they can cause significant damage. Ranging in size from 1/2 to 1 mm long, you could 15 to 30 or more of them nose-to-tail across a dime. If you were to look at one with a magnifying glass, you would see that they are a shiny, creamy white, with four pairs of brown legs.
Bulb mite host plants
As the name implies, bulb mites infest bulbs, such as tulips, daffodils, and saffron crocus. They can also be found under the root plate of garlic and onion, or in the crown of spinach plants.
Damage caused by bud mites
Bud mite feeding is not particularly destructive by itself. The problem lies in the wounds created by that feeding. These damaged areas allow organisms responsible for decomposition to get inside your plants, causing them to rot. Overall stunting, leaf distortion, and softened stems are common responses to bud mite feeding.
How to manage bulb mites
Protect your bulbs against bulb mites by inspecting them before planting. Infested bulbs should be destroyed. Crop rotation and the removal of post-harvest plant debris can interrupt this pest’s lifecycle.
If you grow red raspberries, you need to monitor leaves early in the season for yellow rust.
Like its cousin, the bright orange rust seen on the underside of rose leaves, yellow rust is a fungal disease. Unlike many other fungal diseases, this rust only occurs on the outside of plants. This is not the same yellow rust seen on wheat, rye, and barley, which is called stripe rust. Stripe rust is caused by Puccinia striiformis.
Symptoms of yellow rust
Plants infected with yellow rust (Phragmidium rubi-idaei) will initially have yellow pustules, called aecia, on the tops of the lower leaves. These symptoms are usually only seen in spring and early summer. In early to mid-summer, yellow to orange pustules, called uredinia, are found on the underside of leaves. As summer progresses, these growths darken and a black spot can be seen in the middle, if you look closely. You may also see orange spots on the fruit. Similar infections that occur later in the season may be late leaf rust (Pucciniastrum americanum), or the more severe orange rust (Arthuriomyces peckianus). In any case, infected leaves wither and die, reducing the plant's ability to perform photosynthesis. This can reduce crop size significantly.
Yellow rust control
Pruning for good air flow helps leaves and stems dry out, making life more difficult for this fungi. Since yellow rust spores (teliospores) overwinter in fruiting canes, or floricanes, pruning those canes out at the end of the growing season can break this disease triangle. The canes of summer-bearing raspberries won’t produce any more fruit anyway, so you might as well. Just be sure to dispose of the trimmed canes in the trash, and not the compost pile.
Left in place, these spores then spread the infection to the next season’s primocanes, or vegetative growth. Also, keep the area around the plants clear of dead leaves and other plant debris. If your raspberries are especially prone to yellow rust, you may want to cut the first spring growth of new canes back to ground level. Don’t worry, the root system will put out new canes pretty quickly. That first growth is the most likely to have become infected.
Fixed copper sprays and lime sulfur are recommended for severe outbreaks. Otherwise, you can simply remove infected leaves by hand and improve the air flow between plants to keep this disease in check and protect your delicious raspberries.
Resistant varieties are available, so check with your local Department of Agriculture or Master Gardeners for recommendations for your area.
If you grow peas or lentils, you should know about pea seed-borne mosaic. The same is true for fava beans and chickpeas.
[Sadly, I was unable to find any freely available photos of pea seed-borne mosaic, so you will have to go by the description or search for your own images. The purple-podded peas pictured above are perfectly healthy.]
Symptoms of pea seed-borne mosaic
Stunting, deformation, and rosette-type growths at the ends of stems are all signs of pea seed-borne mosaic. Chlorosis, downward cupping, vein clearing and swelling, and the classic mosaic or mottling of mosaic diseases may all be present in infected plants. Vein clearing is a common symptom of viral infections and it refers to the way leaf veins appear translucent. Seeds tend to be shriveled and discolored. Infected plants are slow to reach maturity, but don’t leave them in the ground long enough to notice. Pea seed-borne mosaic infection is easily mistaken for chemical overspray, nutrient toxicities, and water-stress. Laboratory tests are needed to be sure of infection. You can often take zip-lock bagged samples to your local Department of Agriculture for analysis.
How to control pea seed-borne mosaic
The pea seed-borne mosaic virus (PSbMV) is carried to your garden on aphids. I would tell you to control the aphids, but that is an ongoing battle in the garden. Do the best that you can. Plants infected with pea seed-borne mosaic should be removed immediately. Unfortunately, some infected plants will never show symptoms. As aphids feed on these asymptomatic plants, they then carry the disease to nearby plants, spreading infection. For the most part, as the name implies, this viral disease is carried by infected seeds. Plant infected seeds and the aphids do the rest. To prevent pea seed-borne mosaic from occurring in your garden, only buy clean, disease-free seeds.
This disease can overwinter in nearby weeds, such as shepherd’s purse, vetches, and black medic. It can also be carried on alfalfa and sugar beets without causing the host plants any problems. If you notice outbreaks of pea seed-borne mosaic, and you know your seeds were clean, look at what is growing nearby.
You can prevent pea seed-borne mosaic by planting resistant varieties.
Fig trees can be stately and highly productive, but fig mosaic can take a toll on your fig tree. Fig mosaic is a complex of several, as yet unidentified, viral diseases that all infect Ficus subspecies.
Fig mosaic symptoms
Yellow leaf mosaic patterns are a common symptom of fig mosaic. These patterns are brighter yellow toward the center of each spot, fading to light yellow before reaching the healthy green leaf tissue. As the condition progresses, a rust-colored band appears around the edge of each mosaic spot. Leaves may also be deformed. Infected fruit shows mild mosaic patterning but may be smaller and less abundant than on healthy trees. Most often, fig mosaic causes early fruit drop, all but eliminating your crop.
How fig mosaic is spread
Fig mosaic is spread by eriophyid mites. As the mites feed, the virus is transmitted through their saliva. Fig mosaic can also be spread by grafting and cuttings.
Fig mosaic management
Trees take time to grow, so having to remove an infected tree is best avoided. Begin by only installing disease-free tree and planting them at the proper depth, giving them the irrigation and food they need to stay healthy. Monitor your fig trees for sign of mite feeding. You will need a 20x hand lens to see these tiny sap-suckers. Fig mite feeding is usually seen around bud scales and young leaves and it often causes a faint russetting. Twig stunting and leaf drop may also occur.
Sulfur treatments and horticultural oils have been shown to control fig mites.
Go take a look at your fig tree to see if mites might be present. If they are, get rid of them so that you can enjoy many years of sweet, delicious figs.
Beetles among your squashes and melons is never a good thing, especially when they carry the squash mosaic virus.
Squash mosaic is second only to cucumber mosaic in damage to cucurbits caused by disease. There are two strains of squash mosaic, strain 1 affects melons most often, while strain 2 prefers squash. In either case, your crop will be lumpy, discolored, and significantly reduced, but still edible.
Crops vulnerable to squash mosaic
All cucurbits are susceptible to squash mosaic. This includes your zucchini and other summer squashes, melons, gourds, cucumbers, and pumpkins. Watermelons, however, are not susceptible to squash mosaic. Some legumes and umbellifers can also become infected with squash mosaic.
Squash mosaic symptoms
Squash mosaic causes a dark green mottling or mosaic pattern on leaves, as well as blistering, yellowing (chlorosis), leaf hardening and distortion, and vein clearing. Vein clearing is a common symptom of viral disease and it refers to the way leaf veins become almost translucent while the rest of the leaf remains green.
Squash mosaic carriers
Unlike other mosaic diseases, squash mosaic is not spread by aphids. Instead, striped and spotted cucumber beetles, leaf beetles, and 28-spotted ladybird beetles are the most common vectors of squash mosaic. Many other beetles are also capable of hosting the virus. As these insects feed, their saliva transfers the virus to the plant. This is why it is so important to remove infected plants right away.
Squash mosaic controls
In addition to removing infected plants, beetle control is important in the prevention of squash mosaic. And beetles can be tough to control. The virus can stay viable inside a beetle for up to 20 days, so it is worth the effort. A single beetle can infect dozens of plants in that time frame. To control beetles, handpicking is always an option, if you are quick enough. You can also use neem oil to kill beetle eggs. Encouraging beneficial predators, such as ladybugs, mantids, and solider bugs, in the garden with fresh water, insectary plants, and little or no chemical use is probably the easiest method of keeping beetle populations within reasonable limits.
Squash mosaic can also be carried on melon seeds, so be sure to get clean, disease-resistant seeds from a reputable supplier (and not that melon from the grocery store).
Certain chenopod weeds, including lambsquarters, goosefoot, Russian thistle, and kochia, provide overwintering sites, so keep these weeds away from your cucurbits.
As with many other viruses, tools, clothing, and other surfaces can also become carriers. To prevent the spread of this disease, sanitize tools regularly and avoid working around plants while they are wet.
Warty zucchinis with skinny leaves may mean the zucchini yellow mosaic virus has infected your plants.
No garden would be complete without the versatile, fast-growing zucchini. A favorite in stir-fry, breads, and the ever popular chocolate zucchini cake, zucchini can be very productive plant, as long as it stays healthy.
Zucchini yellow mosaic symptoms
Whitened leaf veins, mottled, abnormally small leaves with alternating light and dark areas, and deformed, warty fruit are all signs of zucchini yellow mosaic. These are also symptoms of watermelon mosaic and papaya ringspot virus, two viral diseases that often occur at the same time as zucchini yellow mosaic. Watermelon mosaic infections tend to include blistered leaves, while zucchini yellow mosaic has the added symptom of leaf lobes becoming long and narrow, creating a ‘shoestring’ or ferny appearance.
Zucchini yellow mosaic host plants
In addition to infecting zucchini, zucchini yellow mosaic also infects other members of the cucurbit family, including melons, squash, pumpkins, some gourds, cucumbers, cantaloupe, and watermelon. The disease is transmitted by aphids.
Zucchini yellow mosaic management
As anyone who gardens knows, controlling aphids is difficult. These pests seem to appear overnight, in huge numbers. And all it takes is one aphid to get the whole process started. Unfortunately, insecticides are rarely useful in managing zucchini yellow mosaic, because the disease has often been transmitted before you even know the aphids are there. Reflective mulches can be used to discourage aphids, just be sure to remove the reflective material before it gets too hot. Row covers can also be used to reduce access to susceptible plants.
This disease can also be spread on infected garden tools and seeds, so be sure to sanitize your tools regularly and get your seeds from a reputable source (and not that zucchini from the grocery store).
Infected plants should be destroyed and replaced with resistant cultivars.
Since this virus is only viable for a few hours within their aphid carriers, creating a physical barrier of tall, non-host plants around your cucurbits can be enough to prevent the aphids from getting to the plants while the virus is still active.
Speckled, mottled, or otherwise deformed leaves and fruit usually indicate a mosaic disease.
Mosaic diseases are caused by a variety of viruses that can infect the majority of your garden plants. Since these diseases are difficult or impossible to treat, recognizing and removing infected plants right away can help prevent the disease from spreading.
Symptoms of mosaic diseases
The classic mottled appearance of infected leaves is only one symptom of mosaic disease. Leaf cupping, blistering, stunting, crinkling, and other distortions are also common symptoms of mosaic disease. Stems may be shortened, creating a bushy appearance to vines.
Plants infected early in the growing season rarely produce fruit. Interestingly, plants infected later in the season retain their healthy, earlier growth and fruit production, while future growth is distorted. Fruit may also show the same mottling and other distortions seen on leaves. Warty bumps are common.
Plants that host mosaic diseases
It would be easier to list plants that are not affected by mosaic disease. Plants commonly infected with mosaic diseases include:
Common mosaic diseases
While there are dozens (hundreds?) of mosaic diseases, some of the more common varieties include:
Mosaic disease management
Generally speaking, mosaic diseases are not curable. Infected plants should be removed. This means that prevention is a far better course of action.
Depending on the specific virus, it may be carried in to your garden on seeds or tools, or by aphids, dryberry mites, and any number of other sap-sucking pests. Removing weeds that could provide overwintering sites, creating physical barriers with row covers and walls of non-host plants, and regularly sanitizing your tools goes a long way toward preventing mosaic disease from taking hold in your garden, as does buying clean, disease-resistant seeds and plants from reputable suppliers.
While mosaic diseases make plants look funny, the fruit of infected plants is still safe to eat. The viruses responsible for mosaic diseases are not harmful to people.
Growing your own corn makes a dramatic statement in the garden. Reaching 10 to 12 feet in height, modern corn plants grow in tandem with other giants, such as sunflowers and hollyhocks. Unless they become infected with corn stunt.
Corn stunt does not mean ears of corn will suddenly start doing gymnastics over the fence into your neighbor’s yard. Instead, this bacterial disease will infect the phloem of corn plants, reducing them in size and all but eliminating kernel production.
Corn stunt disease complex
Some people see corn stunt as a single disease, while others see it as one part of a complex of three disease, the other two being maize bushy stunt mycoplasma and maize rayado fino virus (MRFV). Yet others include maize chlorotic dwarf virus in the corn stunt complex. Any combination of these diseases can be devastating to your corn crop.
Corn stunt symptoms
Healthy corn plants produce one or two ears of corn, depending on whether they are early or late maturing varieties, respectively. Plants infected with corn stunt are significantly shorter than normal, often only 5 feet tall, and may produce 6 or 7 ears. That may sound great, but it’s not. These ears are small and they do not fill properly, meaning there ends up being a lot of empty spaces. The kernels that do develop are not well attached, in a condition known as “loose tooth ears”. Infected plants will also exhibit pale yellow new leaves at the top. As these leaves mature, they tend to turn reddish.
How corn stunt spreads
Corn stunt is caused by Spiroplasma kunkeliiI, which is carried by leafhoppers. Corn leafhoppers (Dalbulus maidis), in particular, carry this disease with them, spreading it as they feed.
Corn stunt management
You can prevent corn stunt by using reflective mulches that deter leafhoppers. Planting your corn as early as possible in the growing season has been shown to reduce the impact of corn stunt infections. Apparently, the first generation of emerging bacterium are not as effective at spreading the disease as those that occur later in the season. Insecticides are generally not effective.
You don't have to grow corn to have a reason to worry about seed corn maggots.
Seed corn maggots mostly feed on decaying organic material, but sometimes they feed on the roots and seeds of over 50 different garden plants. Also known as the bean seed fly, seed corn maggots may be tiny, but they can ruin several of your crops.
Seed corn maggot description
Seed corn maggots (Delia platura) are small, dark grey flies with grey wings, black legs, three stripes on the back, and scattered bristles. Less than 1/4” long, seed corn maggot adults looks nearly identical to onion maggot flies. White or off-white larvae are legless and have rounded tails and pointed heads. Pupal cases are brown and hard and look like skinny footballs.
Seed corn maggot damage
Seed corn maggots often feed on the seeds of corn, peas, beans, and soybeans but they do not always kill the embryos within the seeds. When those seeds germinate, they are spindly and rarely make it to maturity, wasting valuable resources. Other crops commonly attacked by seed corn maggots include cucumbers, melons, onions, peppers, and potatoes.
Seed corn maggots may tunnel into the stems and roots of many different garden plants and feed on spinach leaves, often providing points of entry for other pests and diseases.
Seed corn maggot lifecycle
Adult flies emerge in spring and begin feeding on nectar and honeydew. After mating, females lay an average of 270 eggs in the soil, near the surface. One week later, larvae emerge and begin feeding. One to three weeks later, larvae move back into the soil where they pupate for one to three weeks, or over the winter.
How to control corn seed maggots
The key to controlling corn seed maggots is in the soil. While I am a proponent of no-dig gardening, repeated appearances of corn seed maggots warrants disturbing the top 2 or 3 inches of soil on a regular basis during the spring and summer months. Research is being conducted on the possibility of beneficial fungi being used to control these pests, but it is not currently an option.
As is nearly always the case, prevention is far easier. You can reduce the odds of seed corn maggots attacking your crops by waiting for the weather to warm up before planting, and spacing plants properly. Anything that slows germination or initial seedling growth makes it easier for seed corn maggots.
Juicy, sweet kernels of corn transform, overnight, into hideous, purple-grey, tumors. And these tumorous galls are delicious!
Introducing, corn smut.
Now, corn has many pests and diseases: corn earworms, European corn borers, seed-corn maggots, soft rot, seed rot, fusarium root and ear rot, maize dwarf mosaic, pythium stalk rot, and damping-off disease, just to name a few. If you are an American corn farmer, corn smut is not what you want to see in your field. A lot of money and effort have gone into eradicating corn smut in North America.
Corn smut in your garden is something else entirely.
While this distant cousin of mushrooms reduces crop size and makes ears of corn unmarketable for July picnics and canning purposes, it is edible and delicious. Unlike other corn problems, corn smut is said to taste like truffles, with a sweet, earthy, inky flavor. If it appears in your garden and you don’t want it, your local chef would love to hear from you!
To my way of thinking, if life gives you lemons, make lemonade. Or, if you are given corn smut, make quesadillas! Corn smut can be eaten raw, or added to many dishes, such as omelets, soups, sauces, meat dishes, or even desserts! As an extra bonus, corn smut is high in lysine. This means eating it with corn, or any other seed, provides a complete dietary protein.
Corn smut description
Also known as devil’s corn, common smut, boil smut, Mexican truffles, or huitlacoche [pronounced weet-la-COH-cheh], corn smut is a parasitic fungus that can occur on any aboveground portion of a corn plant as purplish blobs covered with papery greenish-white tissue. These fungi prefer meristem tissue and the galls are mostly seen on the ears of corn. Ear galls are significantly larger than those which form elsewhere on the corn plant.
Corn smut gets its purple color from pigments called anthocyanins. These are the same pigments found in blueberries, raspberries, and purple cauliflower. When you cook with corn smut, don’t be surprised to see the purple color change to black, because it will. Purple pigments generally don’t hold up well to heat.
Corn smut lifecycle
The corn smut fungus (Ustilago maydis) infects plant ovaries, causing kernels to swell up into large purple galls that are filled with fungal threads, called hyphae, and spores. Corn smut spores are already in the soil and can be carried on the slightest breeze or splashed water from rain or irrigation. Dry conditions and temperatures between 78°F and 93°F are all that corn smut needs to get started. Adding nitrogen or applying manure increases the chance of corn smut developing on your corn plants. Plant injuries also increase infection rates.
Corn plants try to defend themselves against corn smut by blasting the invaders with reactive oxygen (hydrogen peroxide). Sadly, from the corn plant’s perspective, this bubbling action simply spreads the smut spores.
If smut appears on your corn, fear not! Instead, harvest the galls while they are young and have the texture of a foamy popcorn, kind of firm and spongy. These moist galls are ready for harvesting 2 or 3 weeks after infection appears. As the galls mature, they turn dry and are mostly filled with unappetizing dry, black fungal spores.
Love it or hate it, corn smut is here to stay, so you may as well learn to cook with it (or sell it).
With the 4th of July right around the corner, watermelons are a common sight. But watermelon mosaic is something I hope you never see.
Watermelon mosaic (WMV) is a viral disease that can also infect cantaloupes, squash, and other cucurbits, along with some legumes, such as peas and alfalfa, and chenopods. Infected watermelons look like they have ring worm.
There are two different watermelon mosaic viruses: WMV1 and WMV 2. While these are two distinctly different viruses, we are going to throw them together for the sake of this discussion.
Symptoms of watermelon mosaic
Symptoms of watermelon mosaic virus vary by host, but the first sign of infection is light discolorations in the leaves. This irregular chlorosis is usually seen along leaf edges (margins) and along veins. Leaves may also be smaller than normal, deformed, blistered, or wrinkled. That wrinkling is called rugosity. Finally, infected fruit develops a mottled appearance. The mottling looks like light-colored rings just under the skin. Warty growths may also appear. Fruit production is significantly reduced.
How to prevent watermelon mosaic
Spread predominantly by aphids and occasionally leaf miners, watermelon mosaic virus can also be carried on garden tools and clothing, so sanitize your tools regularly. The virus is only able to survive inside aphids for a few hours, so creating physical distance between potential carriers of the virus can also reduce infection. Crop rotation and removing infected plants can break this disease triangle.
Weeds, such as lambsquarters, cheeseweed, goosefoot, and Russian thistle, can act as vectors for this disease, so keep them away from your watermelon and other susceptible plants.
Horticultural oil spray can also interrupt transmission of this virus, but may cause problems of its own.
Insecticides are not effective because the disease is transmitted before the chemicals can kill the carrier. You can use reflective mulches under susceptible plants to repel aphids. If you use reflective mulch, be sure to remove it before the summer sun uses it to cook your plants.
Sometimes plants grow in ways you might not expect.
Instead of a nice round stem or flower, you get a flattened ribbon shape, or undulating folds, called ‘cockscomb’. This is called fasciation. It is also known as cresting.
Fasciation is a relatively rare physiological disorder that can create some really beautiful mutations. It can occur anywhere on a plant, but stems and flowers are the most commonly seen examples.
How does fasciation occur?
In normal plant development, growing tips (apical meristems) focus all their resources on a single point. This is what gives us straight and/or cylindrical stems and flowers. Fasciation elongates the apical meristem, creating a ribbon-like growth. The Latin word fascia means “a band” and can refer to anything that looks like a ribbon or wide band.
In some cases, these distortions can create unique bends, twists, and odd angles, or unusual clusters of growth that look like a witches broom. Flowers and leaves growing on these distorted stems may be smaller than normal, more abundant, or have other unique characteristics of their own.
One rare form of fasciation, called ring fasciation, has a ring-shaped growing point that creates hollow tubes.
What causes fasciation?
Fasciation can be caused by plant hormone imbalances, genetic mutations, environmental conditions, or bacterial, fungal, or viral infections. It can also occur for no apparent reason. Environmental factors include chemical overspray or exposure, mite or other insect infestation, and the presence of certain fungi. Exposure to cold and frost can also cause fasciation. Unless the fasciation is caused by bacteria, it is not contagious to nearby plants.
Plants affected by fasciation
In addition to my milkweed, this condition is most commonly seen on nasturtiums, geraniums, dandelions, and ferns. It has also been seen on fruits and vegetables, such as asparagus and broccoli.
Some plants are prized and propagated simply because of their fasciation. I look at it as a nice little surprise from the garden.
Have you seen fasciation in your garden?
If you grow currants, you should know about currant sawflies.
Currants make delicious jellies, pies, sauces, and even wine, but currant sawfly larvae can completely strip the leaves from your currant plants in only a few days.
Also known as imported currantworms and common gooseberry sawflies, these pests feed on gooseberries and other members of the Ribes family. Native to Europe, this pest is now found throughout North America.
Currant sawfly identification
If you see chewed holes in the leaves of your currant bushes, take a closer look. There are several pests that can cause this damage. It may be currant borers (Synanthedon tipuliformis), currant spanworms (Itame ribearia), the Epochra ribearia maggot, gooseberry fruitworms (Zophodia convolutella), or currant sawflies (Nematus ribesii). Sawflies tend to feed in groups, while those other pests do not.
Like other sawflies, adult currant sawflies look like a cross between a wasp and a fly. The larvae grow to 3” in length, but their coloration makes them difficult to see. They start out green with black heads. As they grow, they develop yellowish ends and black spots.
Currant sawfly lifecycle
Adult currant sawflies lay tiny, oval white eggs on the underside of leaves and there can be three generations each year. The first brood emerges after the first leaves appear in spring, the second occurs in early summer, and a third generation may occur, weather permitting. In each generation, feeding is very heavy and rapid.
To make matters worse, feeding often begins on the lower, inner reaches of the shrub, so you may not even notice the damage right away. Be sure to inspect plants regularly for signs of feeding and look on the underside of leaves for eggs.
How to control currant sawflies
Before you take any drastic measures, you need to know that the larval stages of currant sawflies look a lot like little green caterpillars. The distinction is important because control measures are different for moth and sawfly larvae. Take a closer look. If you have one, grab a hand lens or magnifying glass. If if you see 6 or more pairs of hookless legs, it’s a sawfly. Caterpillars have tiny hooks on their stubby legs and they usually have only 3 pairs of prolegs.
You can treat moth larvae infestations with Bacillus thuringiensis (Bt). That treatment will not work against sawflies. Commercial growers spray plants with Malathion as soon as currant sawflies appear. Your best choice for controlling currant sawflies is to spray infested plants with insecticidal soap and handpick currantworms as they are seen.
When most of us hear the word ‘bicarbonate’ we think of baking soda. In this case, we’d only be half right.
Baking soda (NaHCO3) is sodium bicarbonate. Sodium is salt. Salt is bad for your garden. Period.
Potassium bicarbonate is something else entirely.
What is potassium bicarbonate?
Also known as potassium hydrogen carbonate or potassium acid carbonate, potassium bicarbonate (KHCO3) is a white, alkaline solid used in fire extinguishers, wine making, to make club soda, and to neutralize acids. As a base, potassium bicarbonate is at the high end of the pH scale. If you have alkaline soil, studies have shown that using potassium bicarbonate does not alter sodium levels in your soil, plants, or runoff water. If your garden plants commonly suffer from fungal diseases, potassium bicarbonate may be exactly what they need.
Potassium bicarbonate is an organic fungicide used mostly to prevent fungal diseases, such as Alternaria blight, apple scab, black spot, blights, botrytis, downy mildews, molds, phytophthora, powdery mildew, and Septoria leaf spot. Once these diseases are in place, they are very difficult to get rid of, through potassium bicarbonate can certainly improve the situation.
Research has shown that bicarbonates do, when they cover a leaf completely, slow the growth of and occasionally kill mold spores outright. For potassium bicarbonate to work effectively, it must be in solution. While some people promote the use of homemade mixes that use horticultural oils for this purpose, those oils can lead to phytotoxicity (plant poisoning), oily buildup on the leaves and in the soil, and the mix requires constant shaking to keep the oil and water mixed while applying. The ideal mixture of solution and treatment is sold under the name GreenCure®.
Unlike sodium bicarbonate, which leaves behind a salt residue, ammonium and potassium bicarbonates contain nitrogen, an important plant nutrient.
Can you make your own potassium bicarbonate spray?
You can, but you shouldn't. As a big proponent of DIY just about everything, I must say that this case is an exception to that rule. While you can certainly find recipes for your own potassium bicarbonate spray online, making it properly is not as simple as advertised. The truth is, it took years of research to determine the proper balance of ingredients that allow the antifungal action to occur, while sticking to plants, but not killing them in the process.
The fine folks at The Garden Professors Blog Facebook Page directed me towards some good information along the same lines. Bottom line: potassium bicarbonate is an effective prevention and treatment of many fungal diseases. It is not something you should be making at home. Instead, read labels and buy a product that will protect and not harm your plants.
If you decide to use potassium bicarbonate in your garden, UC Davis recommends no more than 8 treatments a year.
Yellow spots on leaves may indicate Septoria leaf spot.
This fungal disease is very destructive and it affects celery, chicory, cucumber, and other cucurbits, along with asters, carnations, chrysanthemums, verbena, and various trees and shrubs. Septoria leaf spot is one of the most destructive tomato diseases I know.
Like other leaf spot diseases, Septoria reduces photosynthesis and the flow of important nutrients through the vascular bundles, leaving plants to wither and die.
Warm, wet weather is all this fungi needs to set up housekeeping in your garden. And remember, that wetness can be caused by poorly placed sprinklers, leaky hoses, and overhead watering, just as easily as the weather. Temperatures between 60°F and 80°F are ideal for fungal growth. Knowing what to look for can help you protect your plants.
Types of Septoria
Septoria is a family of fungi. Different subspecies affect different plants. The most common types of Septoria, followed by their host plants and symptoms, include:
Symptoms are first seen in older leaves. The disease spreads upward into newer growth. As the spots spread, leaves turn yellow, die, and fall off. This leaf loss reduces plant vigor and increases the chance of fruit being damaged by sunburn. Severe infections can result in complete defoliation.
Septoria leaf spot lifecycle
Septoria fungi travel on the wind and in rain, so it’s something you need to monitor for regularly. Spores come into contact with host plants and send out thready hyphae, which enter plants through cracks and injury sites. Spores overwinter in the soil and on infected plant debris.
How to control Septoria leaf spot
As with many other diseases, prevention is far easier than treating. These tips will help prevent Septoria leaf spot in your garden:
If Septoria leaf spot is seen, remove infected leaves right away and throw them in the trash. Also, sanitize any tools that may have come into contact with infected plants and avoid working around plants when they are wet.
While it might be cute to picture a fly buzzing around with a tiny saw, there is nothing to love about sawflies.
Sawflies get their name because their ovipositor (egg-laying organ) is shaped like a saw and used to cut notches into plants for egg-laying.
Sawfly larvae may look like caterpillars or slugs, but these pests are in the same order as bees, wasps, and ants, and are closely related to woodwasps and horntails. You can tell the difference between sawfly larvae and caterpillars by counting their legs. Caterpillars usually have five or fewer prolegs on their abdomen, while sawfly larvae, such as the California pear sawfly, have 7 or 8 pairs of prolegs on their abdomen and 3 more pair on the thorax.
With over 8,000 sawfly species, spread out over 800 genera, there is a wide variety of coloration and body type in the world of sawflies. As a group, their soft bodies are stubby and only slightly wasp-like, and they tend to be weak flyers. The ovipositor is often mistaken for a stinger, though sawflies cannot sting. Some sawfly larvae, however, are known to puke up a noxious liquid that would-be predators find distasteful, while other sawfly species raise their rear ends up, cobra-fashion, weaving back and forth a warning.
Some of the more common sawfly species include:
Adult sawflies only live for one week, during which time they mate and females lay 30 to 90 eggs. Eggs are tan, oval or kidney-shaped, and look like tiny blisters on the upper surfaces of leaves. In 2 - 8 weeks, depending on temperatures, those eggs hatch and then go through 5 or 6 larval stages, depending on the species, before heading to the soil, en masse, to pupate. Some sawfly species use webspinning and leafrolling to protect their young, while others spin cocoons. The entire process can take 2 years. It is during the larval stages when sawflies do the most damage.
Sawflies are defoliators, which means they strip the leaves from several garden plants. Species tend to be host-specific. Rose sawflies attack roses, pine sawflies attack pine trees, and so on. Plants vulnerable to sawfly feeding include apple, cherry, peach, pear, plum, and quince trees, along with most cane fruits.
Larvae often feed in large groups, for added protection. Damage caused by larval forms of sawflies include leafmining, defoliation, skeletonizing, galls, and notching of leaves.
Generally speaking, handpicking is your best method of controlling sawfly larvae. You can feed them to your chickens for a tasty protein treat, or bag them and toss them in the trash. While Bacillus thuringiensis (Bt) can be used to control moth and butterfly larvae, it is not effective against sawfly larvae.
Insecticides can be used against sawflies, but sawfly larvae are a popular food for many native birds, including partridges, black grouse, corn buntings, and chestnut-backed chickadees. Shrews, lizards and frogs also enjoy snacking on these pests, along with several predatory wasps, including ichneumon and braconid wasps.
You can attract these garden helpers by providing fresh water, growing a variety of insectary plants and plants that provide pollen and nectar, and avoiding the use of broad spectrum pesticides and herbicides.
Blue-green sharpshooters are sap-sucking, disease-carrying cousins of leafhoppers. Native to California, blue-green sharpshooters (Graphocephala atropunctata) have only recently become serious pests.
As blue-green sharpshooters feed, they inject plants with a bacteria that causes Pierce’s disease.
Pierce’s disease primarily affects grapes, but it can also appear on alfalfa, almond, avocado, blackberry, citrus, elderberry, and olive. The bacteria that cause Pierce’s disease block the flow of water and nutrients through the xylem, causing scorching, stunting, bleaching, leaf stippling, “matchstick” petioles, ‘green islands’ on stems, raisined grapes, defoliation and dieback. But symptoms do not always appear in the year the plant is infected. This results in many more plants becoming infected as sharpshooters move from plant to plant as they feed. Plants infected the previous year often exhibit delayed or absent budbreak. Plants infected early in the growing season are more likely to look as though they have recovered, even though they haven’t.
There is no cure for Pierce’s disease and infected plants usually die within 1 to 3 years. Other diseases caused by the same bacteria include almond leaf scorch, oleander leaf scorch, and olive leaf scorch. These bacteria can also be carried by spittlebugs and glassy-winged sharpshooters.
Outbreaks of Pierce’s disease have been growing dramatically. This is believed to be due to warmer temperatures allowing vectors, such as blue-green sharpshooters, and the bacteria they carry, to live through the winter.
Blue-green sharpshooter description
Unlike glassy-winged sharpshooters, which average 1/2” in length, blue-green sharpshooters are much smaller and easy to miss. As far as pests go, the blue-green sharpshooter is quite colorful. From a distance, it simply looks like a wedge-shaped green insect. If you look closely, with a hand lens, you suddenly see striking bright blue to green wings, thorax, and head, with a yellow abdomen and legs. There are sometimes red, yellow, or green markings. You may also be able to see red drops of sap attached to their legs.
Blue-green sharpshooter lifecycle
Until recently, only one generation of blue-green sharpshooter appeared each year. Rising temperatures and stressed predator insects are making multiple generations possible. Most sharpshooters overwinter near creeks, becoming active in spring. Eggs are laid just after budbreak. As surrounding vegetation begins to dry up, concentrations of sharpshooters in gardens, vineyards, and orchards increases. Sharpshooters go through complete metamorphosis, frequently leaving pale discarded exoskeletons behind on the underside of leaves. Nymphs and adults feed on nutrient-rich sap throughout the summer, moving back into nearby weeds and vegetation at the end of summer.
Blue-green sharpshooters use vocalization to communicate and to find a mate. Males have 3 distinct calls: a complex mating call, a gulping call, and a chirping call. Females have a call they use to respond to males’ mating calls. The pair sings a type of duet before mating, which is all very nice, but they still spread disease. Because there is no cure for Pierce’s disease, interrupting the disease cycle is the only way to prevent plant loss.
Controlling blue-green sharpshooters
The first step to controlling blue-green sharpshooters is to make sure they are present. This is done with yellow sticky sheets. Sharpshooters are most commonly found in locations with abundant soil moisture and some shade. Unshaded, dry areas and areas of deep shade are less likely habitats for sharpshooters.
You can reduce the chance of infection of Pierce’s disease with these tips:
Famers have found that installing bluebird boxes goes a long way toward reducing blue-green sharpshooter populations. Insecticides aimed at sharpshooters are only marginally effective, while insecticidal soap and horticultural oil provide some control.
Cereals may show up in boxes on store shelves, but they always start out growing in a field or garden the same way all the other grasses you see coming up in lawns grow.
It is believed that people started cultivating figs some 11,000 years ago and that full-fledged farming of cereal grains started some 8,000 years ago. Many historians attribute modern society to the wealth created by agriculture and farming cereal grains in particular.
We get the word cereal from the Ceres, the Roman goddess of agriculture and the harvest.
Cereal grains include:
A cereal grain is actually a type of fruit called a caryopsis. The seed heads are called ‘ears’, even when you are talking about something other than corn
Combining the fruit of a a cereal grain with a legume provides us with complete proteins needed to stay healthy. This means peanut butter (legume) on wheat bread (cereal), or rice (cereal) and beans (legume) gives us the same amino acids as eating meat [though I will rarely turn down a steak]. Cereal grains contain amino acid chains, called peptides, that bind to the same receptors in our brains as opioid drugs, which may explain why those carbs are so damned addicting.
How cereal grains grow
There are warm season cereals and cool season cereals. Most of them are cool season plants, which means they grow best in mild climates. Of the cool season cereals, there are spring and winter types. Spring types are planted in early spring and then mature in late summer. Winter varieties are planted in autumn, grow for a time, and then go dormant during the winter. When spring rolls around, these plants have a head start on the competition and burst into full flower before maturing in late spring or early summer.
How to grow cereal grains at home
Most cereals are planted by broadcasting seed across a prepared bed and then raking the area to a depth of 2”. The area is then watered thoroughly and then covered with a 2- to 4-inch layer of straw. The straw helps retain moisture and reduces seed loss to birds. It also makes life more difficult for weeds. After that, there isn’t much you need to do. I like growing cereals alongside fences and the house, though you do have to watch out for mealybugs and fungal diseases.
Pests and diseases of cereal grains
Rats, mice, and other rodents, and birds love cereal grains and you will be hard pressed to keep them out of your cereal grain crop. Netting helps, somewhat. Extended rains can lead to blotch disease, rust, and leaf spot. I have also found mealybugs to be a problem.
Harvesting cereal grains
Amber waves of grain isn’t just a line from a song. Field or garden patches of ripening seed heads create a comforting sense of satisfaction. And that’s a good thing, because harvesting cereal grains takes a lot of work. First, the dried stalks, or stover, are cut off, close to soil level, and hung or stacked to finish drying. Then the threshing begins. Threshing breaks the seeds free of the non-seed portion, or chaff. Then the material is tossed into the air on a windy day or in front of a fan to get rid of the chaff.
What would corned beef be without rye?
Completely different from the ryegrass growing in your lawn, rye has a lot more to offer your landscape than just a marbled deli sandwich.
Cousin to wheat and barley, rye is a cereal grain used to make bread, beer, and liquor. Native to Turkey, rye has been cultivated since the Bronze Age and it is considered the hardiest of all the cereal grains.
Rye has a lower gluten content than wheat, and higher fiber content. But, even if you don’t eat it, rye provides many benefits to your soil.
Benefits of growing rye
Rye (Secale cereale) makes an excellent green manure and cover crop, particularly in no-dig gardening environments. Rye grows well in poor soil, especially in sand. A fast grower, rye not only suppresses weeds but it produces allelopathic chemicals that reduce weed growth. Rye also prevents erosion, and its tough, fibrous root system can easily reach depths of nearly 3 feet, and as much as 7 feet deep in sandy soils, helping reduce soil compaction and improving drainage. Rye is also used frequently in crop rotation and in orchards and vineyards as a way to improve soil health.
If you have a patch of really poor soil, plant a mix of rye, hairy vetch, and crimson clover in the autumn. Near the end of winter, cut it all down and leave it where it falls. By late spring, you should be able to grow the best tomatoes in the county on that soil, and those tomato plants will be bothered less by Colorado potato beetles and early blight, due partly to beetles having a hard time moving through the residue and reduced soil splashing.
The rye plant
Similar to wheat, there are winter ryes and spring ryes. Spring ryes are usually used as wind breaks and nurse crops that are cut down before seed heads develop. Winter rye is grown for everything else.
Rye is a rugged plant. It can tolerate drought, flooding, and freezing temperatures. In fact, rye has a surprisingly high tolerance for frost. Winter varieties of rye even contain their own version of antifreeze! Rye plants quickly reach 3 to 6 feet in height, making it an exciting winter crop along fences. Allowed to go through its entire lifecycle, this annual will produce flowers in April and May, with seed heads maturing in May and June, in California. Stalks, or stover, are very fibrous and they break down slowly.
Rye pests and diseases
Rye has very few pests and those it has cause little or no damage. Pests of rye include cereal bugs, cereal chafers, dart moth larvae, fruit flies, gout flies, Hessian flies, leaf beetles, nematodes, and rustic shoulder knot larvae. Rye plants also harbor bird cherry-oat aphids.
The more intriguing side of rye includes is high susceptibility to ergot, a fungal disease. Apparently, eating rye infected with ergot causes hallucinations, convulsions, and witch trials, due to the LSD-like chemicals produced as waste products by the fungi. The infamous Salem Witch Trials are believed to be the result of hungry communities eating rye infected with ergot. Not exactly a recreational drug, ergotism also causes miscarriages and the loss of fingers and toes, and it can kill you. Luckily, ergot isn’t the problem it used to be.
How to grow rye
Unlike other cereal grains, rye is very particular about seed planting depth. Plant it more than 2” deep and the seed will die. You can drill holes in the ground for rye seeds or you can broadcast the seed over an area and rake it in. Keep the area moist, but not soggy, until germination occurs and then you can pretty much leave rye to its own devices.
When seed heads mature, they turn a golden brown and dry on the stalks. You can leave the plants where they are and allow the seeds to feed local birds and other wildlife and reseed the area, or you can cut the stalks and hang them to dry more completely before threshing and winnowing the grain.
Threshing means beating the snot out of the seed heads to break them loose. Winnowing means throwing everything up in the air in a windy (or fan-blown) place to get rid of the non-seed parts, or chaff. This is a very labor-intensive process, but seeing a bowl of rye (or wheat) berries harvested by your hand is a very satisfying experience.
If you grow rye for no other reason, lady bugs love it!
Have you ever peed on a tree?
You may have heard garden lore about peeing on lemon trees to improve tree health and fruit flavor, but is it true? And is it safe? [Mostly yes, and yes.] And what is in that bag of urea, advertised as such an excellent source of nitrogen?
As the human population and the demand for food and water continue to increase, new solutions are being sought. Using urea and urine to fertilize edible plants is one of those solutions. Before you get grossed out, you need to know that urine is practically sterile and it is an important part of the nitrogen cycle. As mammals urinate on the ground, nitrogen fertilizes the soil, helping plants grow.
What is urea?
Our bodies use urea to excrete nitrogen in our urine. Urea is colorless, odorless, soluble in water, and non-toxic. Urea and urine both contain a lot of nitrogen, and all plants need nitrogen to grow and thrive. Nitrogen is the fundamental building block for chlorophyll and plant enzymes and proteins, including a plant’s DNA. Without nitrogen, photosynthesis cannot occur.
Over 90% of the world’s manufactured urea is used in agriculture as the most concentrated, affordable nitrogen source available to plants. Pure urea has an NPK value of 46-0-0. For comparison, ammonium sulphate has an NPK of 21-0-0, followed by blood meal at 13-1-1. On average, human urine has as NPK value of 18-2-5. This means urine contains 18% nitrogen (N), 2% phosphorus (P), and 5% potassium (K). The potassium and phosphorus found in urine, human or otherwise, are in forms that are quickly absorbed by plants.
Keep in mind that nitrogen, in all its forms, is highly mobile and easily leached into ground water. This causes out of control algae blooms and water pollution. Regardless of where you get your nitrogen, don’t add more than is needed. [Get a soil test before adding anything!]
How urea feeds plants
When urea comes into contact with the soil, specific bacteria convert it into ammonia (NH3), ammonium ions (NH4+), and bicarbonate ions (HCO3−). Other bacteria use the Calvin Cycle to oxidize the ammonia, converting it into nitrites, in a process called nitrification. This makes the ammonium and nitrites readily available to plants. It also acidifies the soil slightly.
Research published in the 2007 American Chemical Society [J. Agric. Food Chem.200755218657-8663] reported that cabbage grown with human urine as a fertilizer grew larger than those fertilized with industrial fertilizer. Those same plants showed less insect damage that their commercially fed counterparts, though unfertilized cabbages showed the least amount of insect damage. The same study demonstrated that urine performed equally well as commercial fertilizers on cucumber and barley crops, without increasing the risk of disease. In each case, there was no noticeable change in the flavor of the food being grown. [So much for those lemons! ]
In a similar study, published by Cambridge University Press, larger harvests of amaranth were noted on the crops fed with urine. Other studies have found similar results with beets and tomatoes. In fact, beets grown with urine tend to be 10% larger than those grown with commercial fertilizer.
Top dressing your garden with urea or urine just before it rains or irrigating can add a lot of nitrogen to the soil. If you buy a bag of urea, be sure to keep it tightly closed. Nitrogen evaporates rapidly into the atmosphere and urea absorbs water from the air very quickly. Also, you should know that urea can contain biuret, an impurity that can be phytotoxic, or poisonous to plants.
Did you know that the average adult in the Western world pees enough in a year to fill three bathtubs? That’s a lot of plant food!
But there’s a catch.
Too much fo a good thing can be a bad thing
There is so much nitrogen in urea and urine that it can prevent seeds from germinating and burn seedlings, roots, leaves, and your lawn. This is especially true if a plant’s moisture content is low. Urine also contains salt, which can dehydrate or kill plants. You know those dead spots in the lawn where Fido relieved himself? That damage is nitrogen and salt burn.
If you want to use urine to water and feed your garden, it is a good idea to dilute it first. The recommended dilution is one part urine to 2-8 parts water, depending on who you ask. This nutrient rich mix can then be dispersed using a watering can. If you are taking prescription or recreational drugs, you may want to discuss transference with your doctor or local pharmacist first. Chemicals in our water and food supplies is real.
Otherwise, go unzip yourself at the more mature plants in your backyard, such as that lemon tree, or you can contribute some nitrogen and moisture to the compost pile and conserve some tap water.
You can grow a surprising amount of food in your own yard. Ask me how!