Soybean pests and diseases

Spider mites are the most destructive pest of soybeans, followed by corn earworm moths, Mexican bean beetles, bean leaf beetles, and cyst nematodes. Fungal diseases, such as stem blight, rust, and white mold can infect soybean plants, along with bean yellow mosaic and other viral diseases. But don't let that stop you!


If you have the space, give soybeans a try in your yard!

There are three different bean mosaic diseases that occur here in California: bean common mosaic, cucumber mosaic, and bean yellow mosaic. These are all viral diseases that cause downward cupping and wrinkling of leaves, especially as leaves get older, along with the telltale mosaic pattern. Bean leaves that develop a bright yellow mosaic pattern may be infected with the bean yellow mosaic virus. There are several strains of bean yellow mosaic (BYM). In addition to beans, bean yellow mosaic can infect peas, peanuts, soybeans, black locust, and fenugreek.


Bean yellow mosaic symptoms

You can differentiate between bean yellow and the other mosaic infections because bean yellow has a yellow mosaic, rather than a light or dark green mosaic. Bean yellow mosaic also exhibits as bright yellow spots on leaves. Plants infected at an early stage of development can become severely stunted and should be removed from the garden and tossed in the trash.


Bean yellow mosaic lifecycle

The bean yellow mosaic pathogen is called, very unimaginatively, bean yellow mosaic virus, or BYMV, for short. This poorly named virus commonly overwinters in legume crops, such as fava beans, alfalfa, clovers, and vetch, as well as in certain weeds and gladiolus. The virus moves from plant to plant in aphids. When an aphid feeds on an infected plant, it becomes a carrier, transporting the disease to every plant it feeds on from that point forward.


Since resistant cultivars are not yet available, these tips may help prevent bean yellow mosaic in your garden:

• buy disease-free seeds from reputable suppliers [Do not use grocery store dried beans!]
• avoid using broad spectrum insecticides that kill aphid predators
• start seeds early enough that they reach flowering stage before aphids become a problem
• heavy aphid populations can be treated with insecticidal soap or neem oil
• plant different legume crops as far away from each other as possible
• remove legume weeds from the area
• reflective mulches may reduce the number of aphids attracted to your plants

Finally, if you see an infected plant, trash it.

Legumes are nitrogen-fixing plants that produce many of the foods we eat.


Peas and beans are common legumes. Peanuts, chickpeas, alfalfa, clover, lentils, vetch, mesquite, carob, tamarind, lupins, wisteria, and soybeans are also legumes. The unique behavior that makes legumes so valuable is that most of them are able to convert atmospheric nitrogen into a form that is usable by other plants.


Nitrogen

Over 80% of our atmosphere is made up of nitrogen. Plants are greedy for nitrogen, but they can’t use atmospheric nitrogen. Some plants, our beloved legumes in particular, have developed mutually beneficial relationships with certain bacteria that live on or in their roots. These bacteria are able to combine atmospheric nitrogen with hydrogen to create ammonia, which is then converted into a usable form of nitrogen. This is called the Nitrogen Cycle and is what makes legumes an important part of crop rotation and cover crops. Some people claim that marigold plants interrupt the nitrogen-fixing ability of legumes, but I have not found any research to support those claims.

Fava beans are the broad beans seen in minestrone and not seen in falafel.


One of the only beans available in Europe until the discovery of the Americas, fava beans make an excellent ground cover and a delicious meal. Being a legume, like peas and other beans, fava beans are able to fix atmospheric nitrogen to feed themselves and their neighbors (until seed development begins). Fava beans are a close cousin to vetch.

Fava bean plants

Fava beans can grow to 2- to 5-feet tall on erect stems. They have a taproot and large leaves. Fava beans can tolerate temperatures as low as 20°F. The seeds can even germinate at 40°F! They will grow better if you incorporate some compost into the soil before planting, but they can tolerate our heavy clay soil. The flowers are large and fragrant, attracting many different pollinators to the garden.


How to grow fava beans

Fava beans (Vicia faba) are a cool weather crop, so you will want to start your seeds in September or November, in the Bay Area, for a cover crop or green manure. Crops destined to be eaten should be planted in February and March. Fava bean seeds should be sown one or two inches deep, depending on seed size, and 4- to 5-inches apart. Rows should be 2 or 3 feet apart. Seedlings should be thinned to 8- to 10-inches after germination. Regular irrigation is necessary for full pod set. If it is a wet winter, no irrigation is needed. Mulching around the plants will help keep the soil moist.

How wax beans grow

Beans are self-pollinating annuals. These plants are fun and rewarding to grow. They grow quickly enough to work well as a children’s activity, reaching maturity in only 60 days. What’s really fun about these plants is that they can be grown pretty much anywhere: on a windowsill, in a container, in a straw bale, and in partial shade. Of course, they prefer sunny raised beds or traditional garden rows, but, the point is, these plants are EASY.  Like other legumes, wax beans are able to ‘fix’ atmospheric nitrogen, making it available not only to themselves, but to nearby plants. Of course, this only works until the plant starts producing seeds, then the free lunch is over.


How to grow wax beans 

Like other beans, wax bean seeds are mostly endosperm (plant food). Plant seeds one inch deep and 2 to 4 inches apart. If you grow bush beans (not the canned barbecue product), your plants will get 18 to 24 inches tall and about a foot wide, so thin accordingly. Pole beans, however, can be trained up trellising, fences, lattice, sunflowers, trees, pretty much anything they can wrap their tendrils around, without thinning. They can also be used in the traditional Three Sisters Method, with corn and squash. Trellising pole beans on something that goes over your head looks really nice, with ripe beans hanging down, from overhead. It’s makes picking easy, too! Some people say that planting marigolds nearby can be a problem, claiming that they interrupt the nitrogen-fixing capabilities of legumes, such as peas and beans, but I don’t know if this is true.


Wax bean pests and diseases

When it comes to bean pests, it’s all the usual culprits: cutworms, bagrada bugs, cucumber beetles, weevils, thrips, wireworms, leaf miners, and dried fruit beetles. As delicious as fresh wax beans are, it’s no wonder so many critters are after your harvest. Bindweed can also choke out your bean plants. Common wax bean diseases include anthracnose, bean mosaic, and fusarium wilt. Wax beans should not be planted near soybeans to reduce the likelihood of stem blight.

Lentils are packed with protein and fiber, add nitrogen to the soil, and they are easy to grow.


You see them in bags at the grocery story, but have you ever thought about growing your own lentils? People have been eating lentils for 13,000 years! These members of the pea family are called pulses because they are grown to be harvested as dried beans. Lentils are legumes that can “fix” atmospheric nitrogen, making it available to plant roots. Lentils grow 18 to 24 inches tall and produce small white to light purple flowers. The pods are very small, each containing only one or two seeds, so you will need 4 to 8 lentil plants per person. You can grow lentils in containers, but it takes several plants to get a decent crop.


Lentil varieties
Lentils come in several colors, ranging from brown and black, to yellow, orange, red, pink, and green:

• brown lentils - Indian brown, German, green, continental, Egyptian; light brown lentil most commonly sold in stores; can get mushy if overcooked
• Puy lentils - French green; lentils du Puy; remain firm after cooking, making them excellent for salads; take a little longer to cook; rich flavor
• beluga lentil - black beluga, petite beluga; black lentils that turn shiny when cooked
• red lentils - cooks faster than other lentils; turns from salmon to golden when cooked
• yellow lentils - toor dal, archer dal, tuvar dal, tur dal - ground into flour or cooked; often sold with an oil coating that should be washed off
• pink lentils - masoor dal, masar dal, masur dal; cooks faster than other lentils; turns from salmon to golden when cooked

At 68°F, they will germinate in about 10 days. Seedlings should be thinned to one plant every 4 or 5 inches. Rows should be 18 to 24 inches apart. You may want to use row covers, at first, to protect young plants from pests. Be sure to keep the soil evenly moist, at first. Lentils are very drought tolerant once they get a good start. You may want to provide a low trellis, but it is not necessary. Lentils take 80 to 110 days to reach maturity, depending on weather, soil, and sunlight. Stop watering when the pods begin to dry.


Harvesting lentils

Harvesting lentils is a labor of love. Allow the pods to dry out completely before using. Since each pod only holds one or two seeds, I suggest a good movie, a bowl for lentils, a towel on the floor, and a large pot between your feet to collect the discards. The job of hulling lentils becomes a rhythmic Zen sort of experience, once you find your rhythm. You can also harvest immature lentil pods the same way you would harvest green beans. Lentils can also be sprouted and added to salads.


Lentil pests & diseases

Aphids, weevils, nematodes, armyworms, cutworms, cucumber beetles, loopers, lygus bugs, leafminers, whiteflies, thrips, spider mites, stink bugs, and wireworms may try feasting on your lentils before you do. Insufficient air flow can lead to fungal diseases, such as Alternaria rot, anthracnose, root rot, Botrytis grey mold, leaf spot, collar rot, downy mildews, Fusarium wilt, powdery mildew, and rust. Lentils are also susceptible to viral diseases. These include bean leaf roll virus, bean yellow mosaic, pea seed borne mosaic, cucumber mosaic, broad bean mottle, and broad bean stain. It's a wonder that anything can survive! The best thing you can do to protect your lentils is to provide adequate air flow and monitor your lentils regularly. In spite of the number of threats, lentils are more rugged than they appear.


Lentil trivia

• While lentils normally cook quickly, adding salt or acidic foods to the water can seriously slow things down, so these ingredients should be added last.
• Every August, the folks of Pullman, Washington host a National Lentil Festival.
• The Latin name, lens culinaris, comes from edible lenses, based on their shape.

The rich, earthy flavor of lentils make it an excellent addition to soups, stews, and salads. How about adding some lentils to your landscape this year? Give it a try!

The Three Sisters of Native American agriculture are corn, beans, and squash.


These ‘sustainers of life’ have a rich history of folklore, spirituality, and early agriculture. They also make sense in the garden. The Three Sisters Method of growing is an example of drought tolerant companion planting that has withstood the test of time.


The Three Sisters Method was believed to have been started by the Iroquois, or the Haudenosaunee, found in the northeast region of the Great Lakes region. This collection of five nations spoke similar languages and shared agricultural information. Native Americans relied heavily on winter squash, such as pumpkins, corn (maize), and climbing (or pole) beans for both food and trade goods for several hundred years. This successful growing method spread west and south to what would become Utah, Colorado, Arizona and Mesoamerica.


Benefits of the Three Sisters Method

Planting these three sisters together allows them to benefit each other in several ways:

• corn stalks provide a climbing structure for the beans
• young beans add nitrogen to the soil
• wide prickly leaves of the squash shade the ground, stabilizing temperature, reducing evaporation and competition from weeds, and deterring pests

In some areas, a fourth plant was added to the mix. This was usually a flowering plant used to attract pollinators, such as honey bees, to increase yield. Just as the three plants benefit each other as they grow, eating them together provides fatty acids and the eight essential amino acids needed to form complete proteins.

Planting by the Three Sisters Method

Rather than planting in rows, the Three Sisters Methods calls for flat-topped mounds, 12” high and 20” wide. Several corn seeds would be planted in each mound. In some areas, rotten fish or eels would be added at the same time, to act as fertilizer. Some areas planted all three types of seeds at the same time. Others would wait until the corn was 6” tall before adding squash and beans. Seeds would be alternately planted around the corn. Two types of beans were used: common beans (Phaseolus vulgaris) and tepary beans (Phaseolus acutifolius), which are more drought tolerant.


You can create your own Three Sisters garden design using the same companion planting concepts. Since corn has higher pollination rates when planted in blocks, rather than rows, you can set aside an area of the yard, or a raised bed, as your very own Three Sisters garden.


The corn will grow up, the beans will climb the corn and add nitrogen to the soil, while the squash protects the ground with its wide leaves. Come autumn, your family will be able to enjoy a high protein meal of beans and corn with a side order of baked or steamed squash, with very little effort on your part.


Give it a try this growing season and see how well it works for you!

Lima beans have the ability to poison their attackers, and groups of lima bean plants work together to counteract threats caused by caterpillars!


The world of plants never ceases to amaze me.


The lowly lima bean, hated by many, loved by some, is a legume. These particular legumes put out chemicals that attract parasitic wasps whenever caterpillars start chewing on their leaves. The wasps lay their eggs in the caterpillars, hatch, and devour their host. Lima beans also contain certain chemicals, stored in different parts of the plant, that become activated when the seeds are chewed, creating potentially fatal cyanide poisoning.

Why grow lima beans?


Despite childhood trauma and potential poisoning, lima beans (Phaseolus lunatus) are actually a very sweet, high fiber source of protein, folic acid, iron, manganese, and potassium. Even better, they are easy to grow and excellent additions to balconies and windowsills, as well as standard gardens. You can select bush or pole varieties. (Sometimes the smaller bush varieties are called butter beans, if that makes them more palatable.)


How to grow lima beans

Lima bean plants will not put out pods in temperatures above 80°F or when it’s cold and wet, so spring and fall are the best times to grow lima beans. Seeds will take 60 to 90 days from planting, so plan accordingly. (Bush varieties take 60 to 80 days; pole varieties take 85 to 90 days). Lima beans prefer a soil pH of 6.0 to 6.8 and full sun, but they can handle partial shade, especially as summer temperatures rise. Surprisingly, too many nutrients in the soil will cause your lima bean plants to produce lots of vegetation, and not very many beans, so you can forego the aged compost. Also, too much water simply makes the beans split, so water sparingly. Plant seeds 1-1/2 to 2 inches deep. Bush beans can be planted 6 inches apart - the plants will actually help hold each other up. Pole beans should be planted 10 inches apart and be sure to provide them with a trellis, tomato cage, fence, or balcony to climb. Pole beans can reach 10 to 12 feet in height. If you need to thin your bean plants, simply cut them off at ground level. The roots have a symbiotic relationship with soil microbes that “fix” atmospheric nitrogen into the soil, feeding nearby plants.


Lima bean pests and diseases

Beans are commonly attacked by aphids, flea beetles, bean beetles, mites, and leafhoppers. Plus, those aphids can carry the bean mosaic virus. Other lima bean diseases include blight and anthracnose. Beans are also susceptible to many diseases found in the soil, so crop rotation is a good idea.


California is responsible for 60 to 80% of the world’s lima bean crop. You can be responsible for 100% of your lima bean crop by growing your own!

Vectors of infection

Bean mosaic is spread by aphids, mealybugs, and leafhoppers. While it sounds convenient, research has shown that using insecticides is not practical because it kills the beneficial insects who would normally feed on the pests. Once a plant is infected, it becomes a vector for disease, as well, and should be completely removed from the site. Infected plants should not be added to the compost pile.


Controlling bean mosaic

Prevention is the best protection when it comes to bean mosaic. Use these handy tips to reduce the likelihood of future generations of beans becoming infected:

• Remove nearby broadleaf weeds. The weeds may provide habitat for the virus and for the vector insects that carry it to your plants.
• Installing reflective mulch may repel insects. You can buy rolls of silver polyethylene from a garden store, or paint some cardboard with silver paint, or lay aluminum foil around your plants for the same results. Just be sure to remove reflective mulch before temperatures get hot or it can cook your plants!
• Buy disease-free seeds from reputable suppliers
• Buy resistant varieties (heirlooms are less likely to be resistant)
• Do not plant beans near clover, alfalfa, rye, or other legumes
• Rotate bean crops each year
• Start plants early enough that they reach flowering stage before aphids become a problem
• Treat heavy aphid infestations with neem oil or insecticidal soap

Bean mosaic is one of the most powerful arguments against using dried beans from the grocery store to plant in your garden. While they are perfectly safe to eat, there is no guarantee that they are safe to sow. Invest in high quality, guaranteed clean seeds from a reputable seller and then save the best seeds from your crop for replanting.

Beans are easy to grow. They improve soil structure, provide excellent food crops, and can look lovely in a landscape, as long as they are kept healthy.

Beans are the edible seeds of the legume family. Often, but not always, these seeds are kidney-shaped. There are over 40,000 different type of beans found in the world. Some of the more common varieties are:

• Vicia faba - fava beans
• Phaseolus lunatus - lima beans
• Phaseolus vulgaris - common beans, including black, pinto, kidney, green, and (my favorite) purple beans
• Vigna angularis - adzuki (or reed mung) bean
• Vigna radiata - mung beans
• Vigna unguiculata - black-eyed pea
• Cider arietinum - chickpea or garbanzo bean
• Pisa sativum - peas
• Lens culinaris - lentils
• Glycine max - soybean
• Cajans cajan - pigeon pea
• Arches hypogaea - peanuts

How's that for a  family tree?


How to grow beans

Growing most beans is really simple. Seeds can be planted 1/2 to 4 inches below soil level, watered a little at first, and then only occasionally afterward. Under ideal conditions, some beans can germinate within just 4 days, making them an excellent crop for children. Beans are not very competitive plants, so you can help your bean plants thrive by regularly weeding the area until they are firmly established.


If you have heavy clay soil, be sure you do not overwater. Clay soil can hold so much water that plants will rot or drown. Now, if you want to get really fancy (and better results), you can inoculate the seeds with a species-specific Rhizobium bacteria. This does not mean giving tiny shots to each and every seed (But it’s a funny image, right?) Beans can be dusted with, rolled in, or briefly soaked in the inoculant at planting time to help them get the most nitrogen out of the soil, for a better start. Personally, I’ve never used inoculants, but many gardeners and most farmers swear by them, especially in areas where beans have not been grown for a long time.


Bean growth habits

Generally, bean plants come in one of two growth habits: bush (determinate) or vine/pole (indeterminate). As with other crops, determinate types tend to flower and develop pods within a set time frame, whereas indeterminate types tend to continue on for longer periods of time, producing pods as they grow. Beans prefer plenty of sunlight, but they can be grown in partial shade, as well.


​Nitrogen boosting beans

Adding beans to a garden or landscape can help fix atmospheric nitrogen into the soil, making it available to other plants (assuming you cut your beans down and let them decompose before they go to seed. Cowpea roots are pretty tough and deep, so they can also help improve soil structure and reduce compaction. Most beans make an excellent cover crop. Beans are also part of the Three Sisters method of growing used by Native Americans. The Three Sisters Method intercrops corn, squash, and beans to make the most of available growing space, soil nutrients, and water resources. The corn grows tall, the beans climb the corn, and the squash shades the ground and reduces weed competition with wide leaves.

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Beans and crop rotation

If you grow beans regularly, it is a good idea to rotate the bean crop with sunflowers, tomatoes, or wheat, to interrupt the life cycle of some fungal pests. Beans are susceptible to damping-off by Pythium, Rhizoctonia, Fusarium, and other pathogens. Thrips and cutworms are common pests. The corn maggot larvae (Delia platura) may gnaw on your planted beans, as well.


Bean seed sources

As tempting as it may be to plant beans that were bought at your local grocery store, this is a bad idea. Those beans can carry diseases that you may never be able to get out of your soil, once they arrive. These diseases are not harmful when eaten by people, but they can be devastating to baby bean plants. Instead, invest in certified bean seed, and then save seed from your crop for next year’s planting!


Nutritious beans

As a food, beans are high in protein, fiber, iron, potassium, thiamine, vitamin B6, and folic acid, with no cholesterol. Wikipedia has an excellent graphic that shows the protein, finer, and iron content of various beans. [Spoiler alert - lentils and kidney beans top the chart!]


Because beans grow so fast, they can be a fun window sill garden addition. 


(And if you want to avoid the undesirable side effects of eating beans, be sure to change the water a few times during soaking and/or cooking. Beano helps, too.)

Black-eyed peas are said to bring good luck when eaten on New Years’ Day, but don’t wait that long! Put them to work in the garden for better growing all year.

Leaf miners are not a specific insect. Instead, they are the larval stage of several moths, sawflies and some beetles. The damage is distinct burrows within leaves, leaving what looks like serpentine, white trails. By feeding within the leaf, leaf miners are protected from predators and pesticides. In fact, applying pesticides actually helps leaf miners by killing off their predators. To make matters worse, all leaf miner species are resistant to carbamates, pyrethroids and organophosphate pesticides.


If you peel back the top layer of an infested leaf, you can actually see the pest, though you may need a magnifying glass.


You can minimize leaf miner damage by planting trap crops. Trap crops are preferred feeding plants. The most common trap crops are:

• lambsquarter
• velvetleaf
• columbine

Also, do not prune unnecessarily, as this stimulates new growth which is more susceptible.

Have the pea plants in your garden turned white?


If you look at the photo below, you will see that new (uninfected) growth is bright green, as it should be. Everything else on the plant looks bleached. That bleaching is caused by a fungal disease known as Fusarium wilt.

Similar to Verticillium wilt, Fusarium wilt is a common vascular disease in which a fungus (Fusarium oxysporum) clogs vascular vessels. It’s pretty much the coronary artery disease of the plant world. In addition to bleaching, common symptoms of Fusarium wilt include chlorosis, stunting, damping-off, brown veins, necrosis, and premature leaf drop.


This soil pathogen is found worldwide and it is spread by water splash, tools, and infected seeds and transplants. Fusarium wilt enters a healthy plant when germinating spores (mycelia) stab at the plant’s root tips and any damaged root tissue. That’s where the really amazing stuff starts to happen!

Fungal life cycle

The Fusarium oxysporum fungus has no known sexual stage. Instead, it produces three different asexual spores: microconidia, macroconidia, and chlamydospores. Basically, the germinating spores (mycelia) inject themselves into a plant’s root system. From there, the mycelia move through the cells of the root cortex and into the xylem (a plant vein). Then, it starts producing the microconidia (asexual spores). The microconidia join the sap stream for a free ride to the rest of the plant. Eventually, there are so many microconidia that a vein is blocked. That’s when they germinate.


The vein blockage stops the plant form absorbing and moving nutrients, so the stomas close, the leaves wilt, everything looks bleached and it dies. As the plant dies, the fungus spreads throughout the plant and sporulates. [Cool word, right? It means “to produce spores”]

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Plants affected by Fusarium wilt

Fusarium wilt attacks a variety of garden plants and the pathogens are specialized according to the victim. Fusarium wilt can attack peas, beans, and other legumes, tomatoes, tobacco, sweet potatoes, cucumber and other cucurbits, and even banana plants!


Fusarium wilt controls

Once a plant is infected with Fusarium wilt, there is nothing to be done except remove the plant and toss it in the trash. Planting resistant varieties in the garden can help prevent Fusarium wilt, but crop rotation is not an effective control method. This is because the chlamydospores can hang out in the soil for a long time. Some fungicides can be marginally effective. 


Since Fusarium oxysporum prefers heavy, moist soil, aeration and adding compost to the garden can bring more oxygen into the soil. This reduces the welcome mat effect for many types of fungus. Ensuring proper drainage is the best way to avoid this garden menace.

Late autumn and early winter often leave our gardens looking bare and unsightly. One way to improve both the appearance and the health of your garden is to use winter cover crops.


Cover crops, also known as green manure, are grasses and legumes that grow quickly. As soon as summer crops are harvested and the last, struggling tomato plant has succumbed to frost, you can plant your cover crops. Any rains that come will help speed their growth. Before they can flower, they are cut back and/or tilled back into the soil.

Legumes are particularly valuable as they add nitrogen to the soil. Popular legume cover crops include Black-eyed peas (pictured above), Fava beans, soy beans, red or crimson clover, and hairy vetch. You can even grow peas and keep trimming the tips (which are excellent in salads) to prevent them from flowering and going to seed. Once a legume has gone to seed, it begins pulling nitrogen from the soil like any other plant. Of course, there's nothing wrong with fresh peas and beans! 


Cover crops also help reduce erosion, suppress weeds, and improve soil health. Inexpensive and easy to grow, cover crops are a simple investment in your garden’s long term health. [They look nice, too!]

Yesterday, I curb-scored 8 very nice tomato cages. While they come in a variety of sizes and shapes, the most common type are concentric circles held at different heights, usually with three legs.