LATE SUMMER INSECTS AND DISEASES TO LOOK FOR
(adapted from Long Island, Massachusetts, New Jersey, and New York Extension)
Spider mites. Keep a lookout for mite infestations in eggplant, tomatoes, potatoes and watermelon. Dry and warm weather keeps mite pressure up on these crops. Focus on older and middle leaves for early signs of damage and treat promptly. Consult your copy New England Vegetable Management Guide for recommendations, or go on-line to: www.nevegetable.org/. The guide contains both conventional and organic recommendations
‘Worms’ in cole crops. Cabbage loopers, diamondback moths and imported cabbageworms are high now. Even weekly applications of Bt insecticides may not be holding up if pressure is high. SpinTor/Entrust, Avaunt and Proclaim are useful for all three. Pyrethroids (Warrior, Danitol, Mustang MAX, Capture/bifenthrin, Baythroid XL etc.) may be fine if loopers and imported cabbageworms dominate.
Spots on pepper fruits. Symptoms of Anthracnose include sunken, circular spots which develop blackish-tan to orange concentric rings as lesions develop. Lesions on stems and leaves appear as grayishbrown spots with dark margins and can easily be overlooked. Control of Anthracnose begins with using clean, disease-free seed and/or transplants. A three-year rotation with non-solanaceous crops is recommended. After harvest, pepper fields should be disced and plowed under thoroughly to bury crop debris. Bacterial spot symptoms start on pepper leaves as small, water-soaked lesions that turn brown and necrotic in the centers. Spots may coalesce and form large blighted areas on leaves and premature defoliation can occur. On fruit, brown lesions can form which have a roughened, cracked wart-like appearance. High temperatures, high relative humidity and rainfall favor bacterial spot development. Loss from Bacterial spot can be reduced somewhat by maintaining high levels of fertility, which will stimulate new growth.
Carrot leaf blights. Alternaria and Cercospora are two soilborne fungal pathogens that may cause early defoliation in carrots reducing yields and making harvest difficult. Both pathogens produce distinct symptoms on carrots. Symptoms of Alternaria include irregular, dark brown to black spots which typically show up on older leaves first. Cercospora leaf spots are round, grayish-brown and are more prevalent on younger foliage. Both leaf blights typically start at the margins of leaflets and as more spots develop leaflets begin to wither and die. Symptoms similar to leaf infections can develop on stems and petioles. Control of both diseases begins with rigorous crop rotation, planting of resistant varieties, and regular scouting with preventative fungicide applications if needed on susceptible varieties.
Potato leafhopper. This is being found in very high numbers in most fields. Go out and flop a plant into the row and shake it, than flop the plant to the other side of the row. Inspect the ground for leaf hoppers that have fallen off the plant onto the ground. This is an easy way to see what is happening in the field. You may have already started to see some burning on susceptible varieties. The edges of the leaves will turn dark brown. Eventually the whole plant will turn brown and die. It's important to pay attention to leaf hopper because they can seriously decrease yield without being very evident. For conventional growers, Phaser and Thionex are the insecticides least toxic to ladybird beetles; this is important for aphid suppression. For organic growers, the options are limited. Pyganic is the only product that is organic certified that will do the job.
Plectosporium or ‘white speck’ of pumpkin and squash. This blight has only recently been showing up in northern growing areas, including Vermont. It causes small, distinct lesions on infected vines, petioles, leaves, handles and fruit. Symptoms include light tan to pure white ‘spindle-shaped’ lesions that have a dry, scabby appearance. These small ‘white specks’ often coalesce to form large, dry scabby whitish-tan areas on infected plant parts. Heavy vine infection can lead to complete defoliation and handle and fruit infection can ruin aesthetic fruit quality. Control of white speck begins with multi-year rotations with crops other than cucurbits. Maximum coverage of foliage and fruit with fungicide applications is necessary for control of White speck once it gets established.
Sweet corn ‘worms.’ Although pressure is low now, we may still see big flights of corn earworm, depending on the weather pattern. Storms from the south tend to bring in higher population of CEW. Pheromone traps should be monitored closely after such a storm. European corn borer flight has decreased. The second generation is tapering off, and night activity is lower due to cool temperatures. Tasseling corn should still be scouted for damage and sprayed if more than 15% of the field has live worms. Remember to only count live worms so you don’t spray for a problem you have already solved! Remember that ECB overwinters in corn stalks and stems of other host plants. When you finish picking chop the stalks and till in plant debris to cut down on next year’s population. Fall armyworm damage is still out there causing an unsightly mess in some locations. However this does not mean the caterpillars are still feeding. As with the borers, base your infestation rating on live worms found. It is easy to spot the frass left by this pest and then find who is causing the damage. If using an insecticide try and pick one to cover all of your pest problems in one spray. Some growers have reported less than effective control using Warrior against fall armyworm. If you are looking for alternatives, Avaunt and Spintor / Entrust have given consistent control of this pest. Overall things have improved for most sweet corn growers since a rocky start in the beginning of the season - prices are still up and people are still buying.
Fusarium in grafted greenhouse tomatoes. A grower submitted samples from mature plants with yellowing leaves on some portions of the plant; this plus symptoms of extended browning all the way up the stem and into the petioles and nodes, identifies Fusarium as the culprit in this plant. This fungus is a common vascular wilt in tomato along with Verticillium wilt. The Maxifort root stock has resistance to some of the races of these fungi, but not all. Also, if the population of pathogenic fungus is high in your soil, the plants are not immune to the disease. The best long term management strategy is to rotate out of tomatoes for a period of at least 3 years. If this is not feasible, you could try "diluting" the soil with more compost. Also, make sure the pH is high enough since this disease prefers acid soils.
DON’T FORGET THE STRAWBERRY FIELDS
Timely irrigation is very important this time of year to ensure good crown expansion, runner production and flower bud initiation for next year. Remember to do leaf tissue analysis if you have not done so already. Applying 20-30 lb/acre of nitrogen in the next week or two can help plants maintain vigorous growth into autumn.
BLUEBERRIES PACK A POWERFUL HEALTH PUNCH
by Frances A. Largeman, RD
Wild blueberries rank number one in antioxidants for fruit, according to the U.S. Department of Agriculture, with a score of more than 13,000 for total antioxidant capacity. Cultivated blueberries are the second highest, with about 9,000 (for comparison, Gala apples score around 3,900). There's no official recommendation for daily antioxidant consumption, but they are known to be important for fighting off free radicals in our body and from the environment. Free radicals cause damage to cells, disrupting the DNA and potentially setting up the body for disease. And the cell damage may be at the root of a host of health issues, from aging to macular degeneration to cancer to Alzheimer's disease. But antioxidants scavenge those free radicals in the body, neutralizing their effects. According to the National Cancer Institute, considerable research suggests that antioxidants may slow or possibly prevent cancer. They also fight inflammation, now known as one of the main causes of diseases like arthritis and cancer.
Besides blueberries, antioxidants are found in vegetables, nuts, grains, legumes, and other fruits. Beta-carotene, lycopene, and vitamins A, C, and E are all classified as antioxidants. But blueberries also are loaded with lesser-known antioxidants. Anthocyanin gives blueberries their vivid color. And another blueberry antioxidant, epicatechin, which is also found in cranberries, can help keep your urinary tract healthy because it prevents bacteria from sticking to the lining of the bladder. Recent studies in lab animals have also highlighted the cholesterol-fighting benefits of another blueberry antioxidant, pterostilbene. And blueberries also contain the antioxidant resveratrol, which is found in red wine, peanuts, grapes, and some berries. Studies are still preliminary, researchers caution, but resveratrol may help fight Alzheimer's disease. If all these health benefits aren't reason enough to add blueberries to your diet, though, the sweet-tart taste of a handful of fresh wild blueberries or a sprinkling of regular berries on your morning cereal should be. (Copyright 2006 Health magazine. July 2006, from: Rutgers Blueberry Bulletin, Vol. XXII, No. 19)
BRAMBLE FIELD DAY
August 24 from 3 -7pm at Nourse Farms, Whately MA. Co-sponsored by UMass Extension and Penn State University, this workshop will focus on practical methods for identifying common field and postharvest bramble diseases and sustainable management options including cultural methods and organic and alternative fungicides. There will also be a walking tour of fall raspberry varieties and a review of summer varieties and their performance in 2006. There is no fee, and two pesticide recertification credits have been awarded for this program. Bring a lawn chair. Please pre-register by contacting Sonia Schloemann at 413-545-4347 or email@example.com.
Mention of pesticides is for information purposes only, no endorsement is intended nor is discrimination against products not mentioned. Always read and follow the label.
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