RAINY SEASON LEADS TO MANY DISEASES
Ann Hazelrigg and Vern Grubinger UVM Extension
This summerís frequent rain and high humidity have resulted in one infection period after another, so fungus diseases are running rampant. As a result, there have been significant losses in many different crops. Once a disease is at epidemic levels, there is little that can be done except cleaning up by removing infected foliage (perennials) or turning under infected crops (annuals). Sanitation is important with many diseases as it can prevent further spread this year and reduce the likelihood of disease in subsequent years. Planting a cover crop after incorporating an infected field will help keep soil and spores from blowing or washing to other locations.
Since prevention is key to managing diseases, spraying heavily-infected plants is not of much use. Fungicides work by protecting healthy tissue from infection, so sprays must be applied way in advance of a crop going down. If you have serious disease problems, itís a good idea to use all the cultural practices at your disposal and then be prepared to scout for the very first signs of disease next year so you can apply timely protection. After a year like this a good rotation plan will be more important than ever. Be sure to positively identify the disease(s) on your farm so you can determine which crops are potential hosts.
If you need help with disease identification in a commercial field in Vermont, send a sample to the Plant Diagnostic Clinic, 235 Hills Building, 105 Carrigan Drive, UVM, Burlington, VT 05405-0082. There is usually a fairly fast turn around. Include your Email address with the sample. Phone (802) 656-0493 or E-mail email@example.com if you have questions about a disease. Most other states offer a similar service through their Extension systems.
In Vermont the tomato leaf spot diseases we are seeing are mainly Septoria and Alternaria (early blight). If you haven't used a fungicide starting around July 1, your plants are probably defoliated. Tilling plants in as soon as harvesting is over will get help the plants decompose quicker and lessen the amount of disease over wintering. Bacterial canker is being reported as a problem in NY and MA, but we have not seen much of it here. Other good news is that late blight of tomatoes and potatoes still has not been seen or heard of it in Vermont -knock on wood! We have had perfect weather for it. Look for white sporulation on the leaf undersides in the early morning.
Pumpkins and squash fields that have had standing water are probably showing signs of Phytophthora fruit rot. This soil borne fungus will cause a rapid death of plants and large round white spots on infected fruits. This disease also infects tomatoes and peppers, and green beans. If a field is infected, disk it in as soon as possible and rotate out of these crops for 3 years. Improving drainage and rotating with non-host crops is the best long term control. Be careful if you harvest and move infected fruit, as they may rot quickly at the new location, spreading the disease to that spot.
Sclerotinia (white mold) is still being found in wet, humid greenhouses. It has been hard to keep humidity down when it is so wet outside. This fungus attacks a lot of different crops. It seems especially common on greenhouse cucumbers. Look for a wilt of plants first then you will typically see a fluffy white canker and fungus lower in the plant or even in the branch axils. This fungus produces long term overwintering structures called sclerotia (looks like black hard mouse droppings) that can live in your green house for many years. If you have an infected plant, bag it up and get it out of the greenhouse BEFORE these sclerotia are produced.
Garlic in storage is showing signs of disease, including Fusarium basal rot. Be sure to carefully inspect your seed stock before planting. This requires peeling some of the cloves to see if they show signs of infection such as brown, depressed areas. If infection levels are high consider purchasing clean seed.
Mummyberry disease in blueberries seems to be increasing in Vermont
over the past few years. Cultural practices to suppress the disease include
applying a deep layer of mulch over fallen berries in the fall, and raking
the mulch to destroy fruiting bodies as they emerge in the Spring.
If this disease has started to get a foothold, consider an early spring fungicide program next year, using Indar or Orbit, or if organic, Serenade.
Comprehensive web sites with photographs of disease symptoms include:
http://www.nysaes.cornell.edu/pp/extension/tfabp/disindx.shtml (for fruits) and
http://vegetablemdonline.ppath.cornell.edu/cropindex.htm (for vegetables)
PUMPKIN AND WINTER SQUASH HARVEST AND STORAGE
(adapted from UMass Extension vegetable newsletter)
Many pumpkins and winter squash will start to mature in the next several weeks if they havenít already. Once the skin is hard, itís a good idea to get fruit harvested, since nothing good is going to happen out in the field where it faces attack by diseases, insects and weather. Early harvest and careful storage is almost always preferable to leaving fruit in the field in Vermont. Even if pumpkins are only just starting to color up, they will continue to ripen off the vine if stored in a well-ventilated barn or greenhouse. The best temperatures for ripening are in the seventies to low eighties. Night temperatures should not drop below the sixties. In a greenhouse, temperature can be managed with ventilation on sunny days. Unless it is quite cool, heat is not likely to be needed if the house is closed up at night. The extra work involved in bringing fruit in early can pay off by increasing marketable yields and prolonging shelf life if stored properly.
When harvesting squash and pumpkins, it is very important to handle the fruit with care to avoid bruising or cutting the skin. Once the rind is bruised or punctured, decay organisms will invade and quickly break it down. Place fruit gently in containers and move bins on pallets. Use gloves to protect both the fruit and the workers. Removal of the stem from squash (butternut, Hubbard, etc.) will also decrease the amount of fruit spoilage because the stems frequently puncture adjacent fruit, facilitating infection. A period of curing after harvest can help extend storage life of squash. This may be done in windrows in the field during a series of warm, dry days, or in a warm dry atmosphere (70 to 80?F) with good air circulation, such as a greenhouse, for up to 2 weeks. Curing before storage helps dry the outer cell layers which inhibits infection and helps clean cuts made during harvest to heal over.
Take care to avoid exposing squash or pumpkin to chilling temperatures. Chilling injury occirs when these crops are exposed to temperatures below 50 degrees F in the field or in storage. Injury is worse when temperature decreases and/or length of chilling time increases.
After curing, squash or pumpkins should be stored in a dry, well-ventilated area. Avoid tight packing, which limits air movement and can lead to condensation on fruit, or piling fruit too high, which can cause pressure bruises. The ideal storage conditions are 55 to 60?F with a relative humidity of 50 to 70%. Lower relative humidity increases water loss, resulting in reduced weight, and if excessive, shriveling of fruit. High relative humidity provides a favorable environment for fungal and bacterial decay organisms. Under ideal conditions, disease-free pumpkins should have a storage life of 2 months and butternut squash up to 3 or 4 months. Even without the ideal conditions, storage in a shady, dry location, with fruit off the ground or the floor, is preferable to leaving fruit out in the field.
SIGN-UP DEADLINES FOR NRCS COST-SHARE PROGRAMS
October 1, 2004 is the cut-off date for Environmental Quality Incentives Program (EQIP) applications to be included in the next round of ranking and December 1, 2004 is the cut-off date for Wildlife Habitat Improvement Program (WHIP) applications. Land owners who wish to be considered for funding under either of these programs need to get their applications into their local NRCS (Natural Resources Conservation Service) field office. The EQIP program helps reimburse farmers for installing conservation practices to improve animal waste management, grazing land, soil erosion and sediment control, and other environmental concerns. Under WHIP, habitat for fish and wildlife is improved through the installation of conservation measures. For more information contact Dave Hoyt at (802) 951-6795.
TWILIGHT MEETING AT CEDAR CIRCLE FARM
Wednesday, September 8th, 5-7pm, Cedar Circle Farm (CCF) in East Thetford, Vermont, is an organic vegetable, strawberry and flower farm that also offers educational programs with a focus on training new farmers. CCF has 10 greenhouses and 50 acres in production, with an extensive roadside market. CCF works with youth at risk from Worcester MA who come to the farm with the YMCA. This year CCF is conducting a SARE-funded demonstration project on the use of the speciality legume cover crops Black-eyed Mississippi Pinkeye peas. The purpose of the project is to test whether cover crops can be harvested for economic benefit and still enrich the soil. Come learn about the different programs at CCF. Directions: Take Exit 14 off I-91. Turn east onto Route 113, go about one mile. Turn right (south) onto Route 5. Proceed for a few blocks and look for the farm stand sign, where you turn left onto Pavillion Road. The farm is ¼ mile up the road; park at the farm stand. For more info visit www.cedarcirclefarm.org
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