East-Central Region IPM Update

May 26, 2000
The region has experienced such a variety of weather conditions recently, everything from dry conditions, wet and flooded fields, wind and hail. Dry conditions or insufficient moisture can result in a calcium deficiency in actively growing fruit cells. This deficiency can cause blossom end rot in tomatoes and cucurbit fruit. Preven- t-ative measures include supplying even amounts of moisture and fertility during the growing season. Wet fields, and cooler temperatures in some areas of the region may encourage development of soilborne pathogens like Pythium spp. and Phytophthora spp. that can attack young seedlings and transplants. Blossom drop or abortion of flowers is caused by a variety of stresses that young vegetable plants have been exposed to lately. One such stress is excessive wind. Be aware that high winds over most of the region may be responsible for blossom drop on early planted vegetables and fruits if they were blooming. Wind carrying soil particles like sand can also be very abrasive to plant tissue, causing tears in leaf tissue. Soil blowing into a plant can also pit the stem and foliage by eroding away the outer protective cuticle of leaf and stems. Wind damage can cause affected tissue to turn brown. This past week, many areas of the region experienced hail. Hail can also damage plants by shredding or causing tears in the leaf tissue. Severe hail can cause the breakage of young seedlings.

An effective method for staying aware of changing crop-growth stages, weather-related damage, and pest populations in your fields is scouting and monitoring them on a regular basis. Depending on the pest and part of the growing season, "regular" could mean anywhere from weekly (for most diseases) to twice weekly (for insects like Colorado potato beetle). This season, the University of Illinois Extension has placed Distance Digital Diagnositic equipment in all Extension Unit offices around the state (See "High Tech Pest Diagnostics"). Please feel free to use this system as a means of support for identification of insects, weeds, and diseases. When bringing in a diseased plant for photographing and diagnosing, be sure to bring in the entire plant, roots and all. Wash roots lightly so that the color of the root system can be photographed. Dis-colored roots will indicate a pathogen infection. The stem of the plant needs to be split in two so that the vascular system can be exposed and photographed up close to reveal if any vascular discoloration exits. Healthy stems are white, while any discoloration (brown, black, or grayish) is an indication of a vascular infection. Photograph the entire leaf and then focus close up on one lesion.--Loretta Ortiz-Ribbing

Author: Loretta Ortiz-Ribbing