Monroe County agriculture: Tips to curb tomato diseases

MONROE COUNTY — Weather forecast for agriculture, by the National Weather Service’ Climate Predication Center, is calling for a probability for above normal temperatures in its eight- to 14-day outlook for July 17-23, updated July 9. It is also leaning to below normal chances for precipitation. The three-to four-week forecast for July 10 to Aug. 3 is calling above normal temperatures and normal precipitation.

As of July 10, the MSU Enviroweather station at Applewood Orchards south of Deerfield has accumulated 1425.3 growing degree day (heat units), (base 50oF) since April 1. This compares to 1190 GDD last year and a five-year average of 1297 GDD. Rainfall at the same site, and since April 1, has been 11.69 inches, over 186 hours, compared to 6.35 inches last year and a five-year average of 8.96 inches. The rainfall does not include the downpours from Hurricane Beryl.

Mid-season flooding due to rains from Hurricane Beryl, and other events, can lead to ponding and flooding in crops. How long will the crop survive in standing water? If air temperatures are warm and soils are saturated with water, plant respiration rates will increase, causing oxygen levels to decline and further stress plants. Amy Timmerman of the University of Nebraska says corn plants in the V7 to v10 growth stages could survive seven to 10 days if air temperatures do not exceed 86oF. Soybeans should have minimal yield losses if flooding lasts less than 48 hours. Flooded plants will have fewer nodes; plants will be shorter and may have pronounced root diseases.

Tar spot can be a devastating disease in corn. Although it can be found in some fields now, Dr. Marty Chilvers of MSU suggests holding off on any single fungicide applications until corn is at the VT (tassel) growth stage, or the R3, milk stage, to better protect leaves and support grain development. Tar spot is favored by more moisture events, either from irrigation or rainfall. As of July 10, the Penn State Head Scab Model was still up and running, which can be a diagnostic tool for Gibberella ear rot in corn, which is the same pathogen that causes head scab of wheat. Infection of corn comes at silking time, though testing is done by elevators in the fall for DON (deoxynivalenol) or vomitoxin. Therefore, farmers can use this diagnostic tool to help assess the risk for vomitoxin in corn this year and spray during silking (R1), if necessary. Mycotoxins, such as vomitoxin, can be harmful to both humans and animals, which is why testing can determine the ultimate use for the corn. Farmers should also be scouting for corn earworm, Japanese beetles and western bean cutworm, depending on the corn variety planted and any transgenic resistance.

Tomatoes and peppers belong to the Solanaceae family (Nightshade family) and are related to eggplants, potatoes and tobacco. Both crops are wind-pollinated, so air movement of the blooms will assist pollination. Solanaceae crops should be rotated around the garden and not planted in the same space each year to prevent buildup of disease.

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Ten common tomato problems/diseases include: blossom end rot, cat facing, blossom drop, cracked fruit, sunscald, yellow, spotty or wilted foliage, dark spots on fruit, leaf roll, poor fruit set and nibbled fruit.

Blossom end rot appears as a round, sunken, water-soaked spot which develops on the bottom of the fruit. This disease results from a lack of calcium in the developing fruit, slowed growth and damaged roots.  To prevent future blossom end rot, maintain uniform soil moisture, do not cultivate too close to the plant or deeper than one-inch, plant in well-drained soils and avoid using high-nitrogen fertilizers or large quantities of fresh manure.

— Ned Birkey is an MSU Extension educator emeritus and a regular contributor to The Monroe News.

This article originally appeared on The Monroe News: Ned Birkey gives agriculture tips for tomatoes, tar spot