|
Q. For three years I have tried raising rhubarb. It does fine for about three months and then begins to wilt and die very rapidly. This year I moved it to a new location to no avail. I have fertilized using manure and still no luck. I have purchased my plants from a reputable nursery and also tried planting bare-root stock.
- E. V., Arnold, MO
A. Usually, rhubarb is relatively trouble free. There are a few diseases that attack it; one is verticillium wilt. Cut open one of the stalks; if this disease is the culprit, then the veins running through the stalks will be darkened. There is no cure once the plant is infected. To minimize problems, choose a new site for your rhubarb plants that has well-drained soil, preferably in raised beds that warm up early in the spring. To reduce the volume of disease spores in the soil, remove all crop debris at the end of the season, because verticillium overwinters on old leaves and stems. You might try adding generous amounts of compost to the planting area, and spraying plants once a week with a compost "tea" or seaweed extract, both of which exhibit some fungicidal properties and provide nutrients. Use only aged (composted) manure in your garden.
<< Back to FAQs
|
Buy Safer Brand® Garden Fungicide
|
Q. Last year, we grew beautiful pumpkin vines and fruit, but when went to harvest them (before the first frost) the pumpkins had turned to mush. What did we do wrong, and how can we prevent this from happening again?
- I. C., Morganfield, KY
A. When fruit is in contact with moist soil for long periods of time, rot organisms such as phytophthora blight can cause problems. Soft sunken spots form where the fruit touches the soil, and if the conditions are good for the fungus, it can cause complete collapse of the fruit. The rot can also start where the fruit has been wounded by pests or rough handling. To minimize the problem, prop the pumpkins up off the ground with bricks or other braces so they are not in contact with moist soil. Use care when doing this, though, so you don't break the vines or crack the stems.
<< Back to FAQs
|
Buy Safer Brand® Garden Fungicide
|
Q. What are the symptoms of tobacco mosaic virus, how does the disease spread, is there a possibility of a tobacco chewer starting an outbreak?
- B. D., Schenectady, NY
A. "Mosaic infects members of the nightshade family which includes tomatoes and many common weeds along with cucumbers, melons, squash, pumpkin, pepper, spinach, and many other vegetables, flowers, and weeds. Symptoms of a virus infection include light and dark green mottled areas on the leaves, unusual leaf thickening, stunting, and sometimes distorted, fernlike foliage. Although the virus doesn't usually kill plants, it can reduce yields dramatically, and if affected plants are allowed to remain in the garden, the virus can persist for years in the soil.
Mosaic virus is spread by contact -- by gardeners, visitors, or insects. It would be possible, for example, for tomato plants to be infected with the virus after being touched by a person who smokes or chews or by contact with any form of tobacco. Insects may also transmit it from plant to plant.
The control measures are basically related to garden sanitation and prevention. Some gardeners will actually exclude all tobacco and people who handle it from the garden, but in any case remove infected plants and burn them, control surrounding weeds, wash your hands and tools with detergent, use fresh soil and clean equipment for seedlings or if you purchase them be sure they are virus free, grow resistant varieties. In some instances controlling insect pests will also help."
<< Back to FAQs
|
Buy Concern® Garden Defense Multi-Purpose Spray
|
Q. My green peppers are doing beautifully! However, when I leave the green ones on to color up, the peppers get soft, then fall off before they fully ripen. It does not appear to be sun damage because they are shaded by the foliage.
- C. B., Sewickley, PA
A. "There are several problems that can beset peppers as they ripen, especially in wet weather. One likely problem in this case is actually called ripe rot, which is caused by a fungus that does not become apparent until the peppers are in the ripening stage. You may not be able to avoid this problem if the weather continues to be rainy, but by harvesting the peppers before they reach full maturity, you can at least save some of your crop.
At the end of the growing season, pull and destroy the plants (burn or bury them deeply). Next year, plant your peppers in a different area of the garden, and heat-treat the seed before sowing to kill any spores that may be present. Using a thermometer, heat water to 125F (52C), and soak the seeds for 30 minutes."
<< Back to FAQs
|
|
Q. I've heard that harvesting crops such as beans when the plants are wet causes disease problems. Is this true?
- D. N., Boiling Springs, PA
A. Harvesting when foliage is wet does not cause disease in and of itself. But it is a good idea to avoid working in the garden when plants are wet because your activity can transfer disease spores among plants. Most plant diseases require wet leaf surfaces for infection to take place.
<< Back to FAQs
|
|
Q. I was looking for a way to combat the insect that is making small holes in my eggplant leaves and someone suggested growing plants under floating row covers. What are they and how do I use them?
- J. B., Berlin, CT
A. Floating row covers are sheets of lightweight polyester fabric that allow water, light and air in, but, properly secured, keep out insects and other pests. The fabric essentially "floats" over the plants as they grow. To use them, cover the plants and secure the edges of the fabric to the soil, either by burying the edges in the soil, with stones, or with metal soil staples. Row covers are ususally left on as long as necessary to protect the plants from particular insects. For flea beetles, the insects causing holes in your eggplant, leave the row covers on for the first 6 weeks or so. If a very hot spell comes along, remove the covers so the heat doesn't build up underneath. If you use row covers on crops that are insect-pollinated, such as squash, you'll need to remove the covers when the flowers appear, so the bees can do their work. Row covers can be stored and reused over and over.
<< Back to FAQs
|
Buy Concern® Garden Defense Multi-Purpose Spray
|
Q. I've been told my cabbage has downy mildew. What should I spray it with?
- J. K., Pleasanton, CA
A. "Downy mildew affects all cultivated plants and weeds in the crucifer family. Plants can be infected at any stage of development. In seed beds, cotyledons and primary leaves are invaded resulting in fungal growth visible on the underside of the leaf. Later a slight yellowing develops opposite the fungal growth on the upper side of the leaf. The young leaf or cotyledon, when yellow, may drop off.
Older leaves usually persist and infected areas gradually enlarge, turn bright yellow, then become tan and papery. Rarely the affected leaf may develop hundreds of minute darkened specks. Under cool, moist conditions, a white mildew growth can be seen on the underside of infected leaf lesions.
The fungus causing downy mildew in crucifers, Peronospora parasitica, overwinters in roots or in decaying portions of diseased plants. Thick-walled resting spores may form in stems, cotyledons, and other fleshy parts of infected host plants. On growing plants, the fungus produces large numbers of spores that are blown about by wind and splashed by rain. Moisture and temperature are important in the spread and reproduction of this fungus. High relative humidity during cool or warm, but not hot, periods promotes its growth and sporulation. Presence of a water film on the foliage from fog, drizzling rain, or dew allows spores to germinate, infect, and produce more spores on a susceptible host in as few as 4 days.
To avoid, use a crop rotation plan that excludes production of any type of cruciferous crop for at least 2 out of every 3 years. And practice sanitary measures such as the use of clean seed beds away from other crucifer production and the destruction of cruciferous weeds. You may also want to plant disease resistant varieties of cabbage and broccoli.
Copper-based fungicides can prevent the spread of the disease but won't restore the health of your infected plants."
<< Back to FAQs
|
Buy Concern® Copper Soap Fungicide™
|
Q. Ours and our neighbor's summer squash have gnarled and lumpy blossom ends. What is wrong?
- J. M., Chico, CA
A. "A few possibilities come to mind. If the baby squash are just emerging, it could be that the female blossoms weren't pollinated. This sometimes happens early in the season, before the male blossoms appear. It can also happen during cool spells when pollinators are less active.
However, it could be a fungal or bacterial disease. The wet scar formed when the flower detaches from the fruit is a prime site for infection if conditions are right. Cultural techniques like not overwatering, using a drip watering system rather than constant overhead sprinkling (wet plants create a perfect environment for disease), and growing vines on a trellis to improve air circulation all will help significantly. Mulching with a layer of dry organic material such as straw can help reduce the problem somewhat but is not a 100% solution. Try these cultural practices and see if there's improvement."
<< Back to FAQs
|
Buy Concern® Copper Soap Fungicide™
|
|
Q. What is companion planting? Which vegetables grow best together?
- B. S., Arkadelphia, AR
A. "Companion plants are those that have similar growing requirements. In addition, some plants seem to enhance the growth of other plants. For example, some plants repel certain insects, some provide nutrients which benefit other plants, and some just look good when planted side by side.
Marigolds are often recommended to repel insects, protecting nearby crops. Brussels sprouts intercropped with white clover usually attract fewer aphids. You might try growing potatoes and nasturtiums for fewer potato beetles, or peppers and catnip to deter aphids. The combination of cabbage and anise might result in fewer cabbage worms. And broccoli grown with radish should reduce the incidence of green peach aphids. There are entire books devoted to this topic if you want to do some more research."
<< Back to FAQs
|
|
Q. Last summer, the bottom leaves of my pole beans turned yellow and developed brownish spots with light yellow halos. The leaves eventually died and the disease spread up the plants. Can I prevent the problem this year?
A. "Those are classic symptoms of a common bacterial disease called halo blight. This disease thrives in high humidity with temperatures in the low 70s. It's mostly a problem east of the Rocky Mountains and is spread primarily by infected seed or plant debris left on the soil. Infection usually begins with small, brown, angular, water-soaked spots on the lower leaves. The spots later expand and the leaves turn yellow, sometimes producing the characteristic halos around the spots. The disease can eventually defoliate the plant and infect the bean pods.
If you notice the disease on young plants, pull them up, destroy them and replant. Consider growing less-susceptible varieties such as Blue Lake. If the plants are already producing beans when the disease strikes, harvest what you can, then destroy the plants as soon as production begins to decline. In the future, try the following preventive steps. Buy disease-free seed from a reputable company. Plant beans in the same ground only once every three years. Choose a spot where they'll get morning sun so foliage dries quickly. Use a wider spacing between plants for air circulation. And don't work in the bean patch when it's wet."
<< Back to FAQs
|
|
Q. Last year I had problems with basil plants I started from seed and those that I purchased as transplants. The plants grew fine until they were about 10 inches tall. Then they quickly became limp, the leaves fell off, and we were left with brown stems. What are we doing wrong?
- D. F., North Brunswick, NJ
A. "Unfortunately, based on your description it sounds like your basil has been attacked by a nasty soilborne pathogenic fungus, basil fusarium wilt (Fusarium oxysporum f. sp. basilicum). Infected plants grow normally just as you describe until they are six to twelve inches tall, then they wilt. Symptoms can include brown streaks on the stems, discolored stem tissue, and sudden leaf drop. Mints can also carry the fungus although they will not show signs of it. This is initially introduced primarily through infected seed and then lives in the soil for up to 12 years.
The problem with fusarium in basil has been increasing in recent years; breeders have now developed at least one new variety, 'Nufar,' that has shown resistance to the disease. Other ways to deal with the problem include avoiding growing basil (or mint) in that spot again, and growing other varieties of basil besides the common sweet basil. Apparently some of the specialty basils (such as lemon and purple basil) have shown some resistance to the disease."
<< Back to FAQs
|
Buy Concern® Copper Soap Fungicide™
|
|
|
|
