August 15, 1999
Compiled by Vern Grubinger, University of Vermont Extension
(802) 257-7967

EYE ON THE GROUND (Pam Adams, IPM Scout)
Corn Earworm has spread north from Brandon to Starksboro. Cabbage Looper was also seen in Starksboro. Hornworms, and/or hornworm damage were found in field tomato crops in Hinesburg, Starksboro, Brandon and Grand Isle. In Brandon, large populations of aphids are attacking potato plants. Corn Leaf Aphids have recently been seen in Essex and Brandon in large numbers. Whiteflies are out on eggplant and beans, but no damage has been seen as of yet. Two?Spotted Spider Mites were seen on blueberries in Charlotte. Striped and Spotted Cucumber Beetles are still around and are causing scarring of fruit in cucurbits. Japanese Beetles and Asiatic Beetles are damaging crops statewide; control measures should be considered as these can completely defoliate plants. The weather has been perfect for growth of Powdery Mildew. So far, it has been seen in Essex and Shoreham. It is good to scout for Late Blight in solanaceous crops now, as it could be showing up soon.

Some severe Phythopthora fruit rot on pumpkins and squash has been diagnosed. Usually first shows up in low spots where soils remain wet. Plants wilt and fruit have white fungal growth on them Also heavy feeding on peppers by the Asiatic Garden Beetle. The coppery colored beetles hide around the base of the plants in the heat of the day and feed at night. Some heavy 3 lined potato beetle damage on solanaceous ornamentals. (Ann Hazelrigg)

This disease has been observed on several farms. Its causes small raised brown bumps on fruit as well as sunken craters about an eight of an inch wide that become filled with olive-colored fungal growth. A two to three-year rotation out of cucurbits is essential to control. Once this problem appears, lack of rotation can result in epidemic levels of the disease in subsequent years. Fungicides are an option but days to harvest requirements and rapid growth of fruit limit their usefulness.

This problem is fairly widespread this year. According to The Physiology of Vegetable Crops, edited by H.C. Wien "Loss of flower buds and fruit is a problem occurring primarily in the production of large-fruited bell peppers...The most common cause of flower and flower bud abscission in pepper is high air temperature...High night temperatures are more detrimental to fruit set than high day temperatures. When high temperature is combined with moisture stress, abscission is further increased, although moisture stress at moderate temperatures is not generally sufficient for complete reproductive structure loss...Excess nitrogen fertilizer is frequently blamed by growers for poor fruit set under field conditions yet evidence for this is difficult to find." The text also indicates that viruses, fungal pathogens and insect pests such as leafhoppers can cause reproductive structures to fall off.

AGE YOUR BLUEBERRY MULCH (Barb Goulart, Penn State)
We've seen blueberries look like they had a blow torch taken to them after applying fresh sawdust. (This can also happen with fresh chips). I suspect that there's some chemical material, probably in particular types of wood, that is responsible, since I've never seen it happen when the sawdust was allowed to sit out in the weather for a couple of years. Any mulch will help you a good bit. . .you can even use straw. . .the main disadvantage to using something like straw is that it deposes so quickly that it has to be replaced quickly.

TOMATO CRACKING AND RUSSETING (from 1999 NJ Vegetable Recommendations)
Fruit cracking is due to the rapid uptake of water by the fruit, resulting in enlargement of cells and separation of the epidermis of the fruit. Water can be taken up by the fruit through the roots and vascular system or through the fruit tissue around the stem scar. The type of cracking (concentric cracks around the stem, radial cracks radiating out from the stem, or diagonal or transverse cracks across the fruit) is determined primarily by fruit structure and variety. More than one type of cracking may be present in a variety or an individual fruit. The severity of cracking is determined by rainfall and irrigation amounts, variety and stage of maturity. As the fruit ripens, the strength of bonding between cells progressively decreases, resulting in more severe cracking. Severity of cracking is increased by high rainfall or irrigation, or frequent low to moderate rainfall, especially following a period of low soil moisture. To minimize cracking, select a crack?resistant variety. Mountain Pride and Mountain Delight are more resistant to cracking than many other varieties. Maintain a high level of calcium in the soil. Keep fruit growing at a uniform rate by maintaining uniform soil moisture levels. Maintain good fruit cover by proper fertilization and fungicide applications. Harvest fruit at the earliest stage of maturity that is acceptable by your market. Russeting or weather checking of the surface of the fruit is caused by the presence of water on the fruit surface for extended periods of time when there are frequent light rainfalls, mist, fog, and dew. Wide fluctuations in temperature of exposed fruit also contribute to russeting. Russeting can cause fruit to be unmarketable. Maintain good fruit cover by proper fertilization and fungicide applications.

Tissue analysis is the best way to determine whether your fertility program is optimal. There are many hungry-looking greenhouse tomatoes out there at this time of year. If the root systems look OK, then nutrient management may be the primary culprit. I have been distributing Ohio State tissue test mailers to greenhouse tomato growers since the mailers were convenient, however, Ohio State is no longer offering this service so please dispose of any test kits you have.You can still submit tomato samples to the UVM Ag Testing Lab for tissue analysis and I will provide fertilizer recommendations. Send 6 complete leaves taken from different plants of similar health. It is important to take all leaves from just below clusters with golf ball size fruit. Enclose in a box or paper envelope (not plastic) with proper sample identification and a $20 check made to UVM. Send to: Ag Testing Lab, Hills Building UVM Burlington VT 05405