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.
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.
With so many family members, it should come as no surprise that there is plenty of variety. Some legumes grow low to the ground in a spreading habit, while others vine, and other stand upright. All legumes are dicots, which means they produce two seed leaves before true leaves appear. It also means that the seeds tend to be made up of two halves. The fruit, nut, or seed of legumes is technically called a pulse. Pulses are grain seeds held within a pod, or simple dry fruits, that develop from a single carpel. Most legume seeds have a “zipper” along one side that opens up when the seed is ripe. This behavior is called dehiscence. These seeds are often rather large and fast-growing, making them an excellent choice when gardening with children.
Legumes as soil amendment
Legumes can be used as a green manure, cover crop, or an edible harvest. When used as a green manure, plants are allowed to reach the flowering stage and are then cut and left where they fall to decompose. This returns valuable nutrients to the soil and improves soil structure. Other legumes are grown as a cover crop to prevent erosion. Most legumes have strong, deep roots that help aerate compacted soil.
Legumes as food
Legumes are a high protein, high fiber food source. Fava beans, wax beans, lentils, lima beans, and wheat are all just a few of the legumes we eat on a daily basis.
Pests and diseases of legume crops
While the pests and diseases of most legumes are more species specific, nearly all legumes are susceptible to Fusarium wilt. Bean mosaic and powdery mildew are common bean and pea diseases. Stinkbugs enjoy legumes and, what makes them worse is that they can also transmit tomato bacterial spot. Weevils and treehoppers are common pests of legumes.
Adding legumes to your garden or landscape can improve the soil, feed nearby plants, and they provide a delicious harvest. Give legumes a try!
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.
Known as broad beans, Windsor beans, field beans, bell beans, and tick beans, fava beans look similar to lima beans and have been cultivated since prehistoric times for food, as a cover crop or green manure, and the seeds can even be roasted and ground as a coffee extender! These plants are prolific producers.
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.
Harvesting fava beans
Fava beans are harvested when they have reached full size but are still green. They can also be left on the vine until they have dried. They take 80 to 100 days to reach maturity. Like Brussels sprouts, fava bean plants mature from the bottom up, so start harvesting from the bottom of the plant and it should keep producing for several months.
Fava beans as cover crop
As nitrogen-fixing legumes with strong taproots, fava beans are well suited for use as a cover crop or green manure crop on heavy clay soil. Allowed to grow through their complete lifecycle, fava beans can prevent erosion and improve soil structure. If used as a green manure, which means cut down and left to lie where they fall, fave bean plants add nutrients to the soil for future crops.
Fava bean sensitivity
Some people are genetically predisposed to a sensitivity to fresh fava beans because they lack a certain enzyme. These individuals are generally men from southern Mediterranean and northern African regions. This condition is called favism. Symptoms include jaundice, back and abdominal pain, and dark urine. Fava beans also contain high levels of tyramine, so individuals taking monoamine oxidase inhibitors should avoid eating them. They also contain oxalic acid, so fava beans should be avoided by those prone to urinary tract stones.
Don’t let favism (or childhood nightmares of lima beans) keep you from trying fava beans in your garden or landscape. Do you have a favorite fava bean recipe? Share it with us in the comments!
We’ve all seen those cans of yellow wax beans in grocery stores, but these plants are easy to grow, they add nitrogen to your soil, and the crisp sweetness of a freshly picked bean far surpasses anything canned.
Wax beans (Phaseolus vulgaris) actually refers to several different yellow-podded members of the common bean family. This family also includes lima beans, kidney beans, pinto beans, and immature ‘green’ beans. It is believed that wax beans got their name because the yellow color looks similar to beeswax, but no one is really sure. Wax beans are available in both bush and pole varieties.
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.
Lentils come in several colors, ranging from brown and black, to yellow, orange, red, pink, and green:
How to grow lentils
Being a cool season crop, lentils (Lens culinaris) can be started two weeks before the last frost date. Lentil seeds should be planted 1/2 to 1 inch deep, and 1 inch apart. Lentils prefer full sun, loose soil, and a pH of 6.0 to 6.5, so you may need to acidify your Bay Area soil. I grow my lentils in raised beds, so pH and compacted soil are not issues. It makes weeding one heck of a lot easier, too!
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 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.
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:
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!
If you planted beans in fall as a cover crop, or in spring as a food crop, you may notice a problem with leaves looking pale, splotchy, and generally unhealthy. Blotchy, puckered bean leaves may indicate a bean mosaic virus.
There are three mosaic viruses in the Bay Area that attack beans:
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:
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, beans, the magical fruit.
The more you eat, the more you…well, you know.
What you may not know about this nutritional powerhouse is that it is crazy easy to grow, germinates at lightening speed, adds nitrogen to the soil, and is just plain fun to watch grow.
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:
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.
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!
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.
Green manures are crops that are cut and either dug back into the soil or allowed to decompose on top of the soil, before they go to seed. Cowpeas will keep adding nitrogen to the soil right up until they start producing baby cowpeas of their own. Then, that nitrogen is absorbed by the plant and put to use. The nice thing about edible cover crops is that, even if you miss the mark and the plant goes to seed, you still get food!
Cover crops are grown for several reasons. They prevent erosion, add organic matter and nitrogen to the soil, reduce weeds and deter some soil borne pests.
Cowpeas are drought tolerant, germinate rapidly, and don’t seem to be bothered by heavy clay soil. In fact, these garden workhorses can be used to break up compacted soil with little to no effort on your part! While these beans prefer sun, they can also be incorporated into shade gardens. Fusarium wilt, aphids, weevils, and pod borers are the most common pests.
Beans have long been used in companion planting or intercropping. Native Americans used the Three Sisters method of growing beans, squash and corn together. The squash shaded the ground, the beans climbed the corn and the corn soared skyward with the shaded ground and nitrogen-rich soil.
How to grow cowpeas
If you have areas of compacted or bare soil, it is simple enough to poke holes in the soil and drop in a cowpea. Cowpeas are not particular. The hole can be 1-4 inches deep. Plants should be spaced 2 to 3 inches apart and protected from birds until they sprout, which can happen in as little as 4 days!
If you are feeling particularly creative or ambitious, you can plant cowpeas into patterns around trees, walkways, or other landscape features. As the plants come up, they will add a new texture to the garden, along with improving the soil structure and nutrient content!
If you have citrus trees, you have leaf miners.
Leaf miners can be found feeding on many edible and ornamental plants, including tomatoes, beans, cole crops, cucurbits, aster, peas, impatiens, petunia and dahlia. While leaf miners are generally not a threat to plant health, they can detract from a plant’s appearance and it is still a good idea to monitor infestations.
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:
Also, do not prune unnecessarily, as this stimulates new growth which is more susceptible.
PEST ALERT: Japanese beetles have found their way to California!
If you ever lived on the East Coast, you’ve probably seen the devastation caused by Japanese beetles. These shiny green and bronze pests skeletonize leaves and can completely defoliate smaller trees and shrubs. If that weren’t bad enough, their larva attack from underground, feeding on root crops and lawn roots.
Japanese beetle identification
Adult Japanese beetles (Popillia japonica Newman) are just under ½” long and slightly less wide. Males tend to be a little smaller than the females. Japanese beetles are easily recognized by their metallic green body and shiny bronze outer wings. They are clumsy flyers. Up close, five small tufts of white hair can be seen on either side of the body. Beetle larva are about 1” long and white, with a small copper-colored head and a larger copper-colored rear end. Like many other grubs, they rest curled up in a C-shape.
Japanese beetle lifecycle
Japanese beetles go through complete metamorphosis. Female beetles burrow into the top 2-4” of soil, normally in turf and lawns, to lay 40-60 eggs throughout an area. These eggs hatch as larva in midsummer. Larval beetles go through 5 molts (or instars), feeding heavily on turf roots and root crops for several months. In the final instar, they reach a pupal stage. The pupae are reddish-brown to tan and ½” wide. The larva often burrow deeper into the soil for winter. Damage to lawns is often the first sign of an infestation. Mature beetles emerge in late spring and early summer to begin feeding above ground and to look for mates.
Destructiveness of Japanese beetles
Adult Japanese beetles attack over 200 garden plants. Every part of the leaf is eaten except the veins, causing skeletonization. Favorite foods include tomatoes, grapes, peppers, roses, cherries, peaches, pears, raspberries, corn, blueberries, beans, and strawberries. For a complete list of host plants, see the Wikipedia page on Japanese beetles. Larval forms of the beetle feed for several months on lawn roots and some root crops. The first sign of Japanese beetle infestation may be dead areas of a lawn. A drench test can be conducted to see if grubs are the cause of the problem.
To perform a drench test, mark off a one square yard area of lawn (3’ x 3’) that includes both healthy and unhealthy grass with a rope or other clear marker. Mix 2-4 tablespoons of liquid dish soap with one gallon of water in a watering can. If the soil is especially dry, two gallons may be needed. Apply the solution evenly within the area. The soapy water will bring insects to the surface. Over the next ten minutes, check the area for visible signs of grubs and other insects.
How to control Japanese beetles
Pheromone traps are not recommended as a control for Japanese beetles. Research has shown that pheromone traps actually attract 25% more beetles than are captured. The majority of attracted beetles end up feeding on plants near the trap, rather than entering it. Beetles can smell the pheromone attractant from 1 kilometer (0.62 miles) away, so this method is counterproductive in areas with heavy populations. It may be effective locally, as we try to nip this potential tidal wave in the bud. Traps should be checked weekly.
Habitats can be modified by adding plants that are resistant or unattractive to Japanese beetles. According to Held (2004), in “Relative Susceptibility of Woody Landscape Plants to Japanese Beetle,” Journal of Arboriculture 30(6), pp. 328-335, dogwood, forsythia and hydrangea are just a few plants that Japanese beetles find distasteful. For a more complete list, see the North Dakota State University page on Japanese beetles.
Biological control can be achieved by introducing nematodes. Specifically, Heterorhabditis bacteriophora and Steinernema glaseri species have been effective. These nematodes are available commercially. They attack the grubs and should be applied in August.
Milky spore disease is also effective against Japanese beetles. This bacteria (Paenibacillus popilliae) is eaten by the grubs and then causes fat depletion, resulting in dead grubs. Milky spore is not available for sale in some states, but it can be used in California.
Insecticides have been used to control Japanese beetles, but timing is critical and the results may be a mixed bag. Systemic insecticides take time to work and must be applied repeatedly.
Japanese beetles were first found in the U.S. in 1916. Since that time, they spread west to the Rocky Mountains. Unfortunately, in 2015, a male and female Japanese beetle were found in Sunnyvale, CA. It was hoped that that was the extent of the infestation, but we won’t know for sure util a few months or even years have passed. If you think you see one of these destructive pests, please the call the Pest Hotline at 1-800-491-1899.
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!
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”]
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 trees!
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, and 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.
I hope this information inspires you to grow more of your own food. You can ask your garden questions on my Home page.