Weather conditions greatly affect the growth and yield of vegetable crops. Wet, cool weather often leads to disease problems. Unfavorable weather can also cause physiological disorders or problems. Common non-infectious, weather-related problems that occur in the vegetable garden include:
Blossom Drop --- Plants fail to set fruit.
Affected Crops: Tomato, pepper, snap beans
Cause: Extremes in temperature and dry conditions may result in poor pollination and cause the flowers to drop from the plant without setting fruit. For example, blossom drop on tomatoes may occur when night temperatures are below 55 F or above 75 F.
Control: Water the plants deeply once a week. Fruit set should increase when temperatures moderate.
Poorly Filled Ears --- Ears of corn are poorly filled.
Affected Crops: Sweet corn, popcorn
Cause: Poorly filled ears result from inadequate pollination. Hot, dry winds and dry soil conditions during pollination may result in poorly filled ears. Improper planting may also affect pollination.
Control: Corn is wind pollinated, plant sweet corn and popcorn in blocks of 4 or more short rows to insure pollination. Water the plants during pollination if the soil is dry.
Bitter Fruit --- Fruit have a bitter taste.
Affected Crops: Cucumbers
Cause: Bitterness develops when plants are subjected to stressful growing conditions. Stressful conditions include high temperatures, drought, and disease problems.
Control: Much of the bitterness may be removed by cutting off the stem end of the cucumber and peeling the remaining portion of the fruit. Bitterness can be reduced by watering plants during dry periods and practicing good disease control. Cucumber varieties differ in their tendency to produce bitter fruit. 'Straight Eight' often produces bitter fruit. 'Sweet Slice' and 'Burpless Hybrid' have fewer problems.
Blossom-End Rot --- A brown or black spot develops on the blossom end of the fruit. Secondary organisms invade the affected tissue and cause the fruit to rot.
Affected Crops: Tomato, pepper, summer squash
Cause: Blossom-end rot is a physiological disorder caused by a lack of calcium in the developing fruit. Wide fluctuations in soil moisture levels impair calcium uptake by the root system. Excessive nitrogen fertilization may also contribute to blossom-end rot.
Control: To reduce blossom-end rot, mulch and water plants during dry weather to maintain uniform soil moisture levels. Avoid over- fertilizing with nitrogen.
Sunscald --- Initial symptoms are shiny white or yellow areas on the sides of the fruit exposed to the sun. Later, the affected tissue dries out and collapses, forming slightly sunken, wrinkled areas. Secondary organisms invade the affected areas causing the fruit to rot.
Affected Crops: Tomato, pepper
Cause: Sunscald occurs on fruit exposed to the sun during periods of extreme heat.
Control: Grow tomatoes in wire cages. Plants grown in cages provide good foliage protection. Also, control foliar diseases of tomatoes and peppers which may defoliate the plants and expose the fruit to direct sunlight.
Split Cabbage Head --- Cabbage head splits when mature.
Affected Crops: Cabbage
Cause: The splitting results from a build-up of water pressure.
Control: Splitting may be prevented by pulling the mature plant upward and gently twisting the plant to break some of the roots, thereby reducing water uptake. Plant only the number of cabbage you can use over a 2- to 3-week period when the crop is mature. Another alternative would be to plant early, mid-season, and late maturing cabbage varieties to prolong the harvest season.
Fruit Cracks --- Radial and concentric cracks at the stem end of the fruit.
Affected Crop: Tomato
Cause: Heavy rainfall or irrigation following a long, dry period promotes rapid growth during ripening. This growth results in cracking. Exposure of tomatoes to high temperatures (above 90 F) and direct sunlight also contribute to cracking. Large-fruited varieties, such as 'Beefsteak,' are more susceptible to cracking.
Control: Cracking can be reduced by providing uniform supplies of moisture to the plants. Mulch and water the plants during dry weather. Also, plant crack-resistant varieties, such as 'Jetstar.'
This article originally appeared in the July 21, 1995 issue, pp. 1995 issue, pp. 110-111.
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