Vegetable gardeners not only have to battle bugs and diseases, but also the weather. There are insecticides to combat the bugs, fungicides to handle the diseases, but all gardeners can do about the weather is just cope. Vegetable problems caused by the weather are numerous and include too much rain, too little rain, too much sun, too high temperatures, and too low temperatures.

One of the more common problems is blossom end rot on tomatoes. The bottom end of the tomato turns black and mold develops. This problem also occurs on squash, watermelon and peppers.

Blossom end rot occurs on all of these vegetables from a lack of calcium in the developing fruit. This is caused by a number of factors, including extreme fluctuations in soil moisture, rapid plant growth early in the season, followed by extended dry periods, and excessive rains that smother root hairs.

High-low temperatures have various effects on some vegetables.

Beans prefer temperatures between 76 and 80. If the maximum temperature is consistently over 85, the flowers will drop off without setting buds. Heat can also cause the blossoms to deteriorate on the plant without falling off. This condition is known as blossom blast.

Cucumbers that are grown in hot, dry weather often produce fruit that is bitter. Bitter fruit does not result from cross-pollination between cucumbers and squash.

Pea plants stop producing pods in hot weather. They grow best with daytime temperatures below 80 and nighttime temperatures below 65.

Broccoli, cauliflower, Brussels sprouts and lettuce and spinach bolt in high temperatures. Bolting or seed stalk formation of broccoli, cauliflower and Brussels sprouts is caused by a combination of 40 and 50 degree weather and by hot weather.

Lettuce bolts when temperatures are above 80 for several days in a row and the leaves become bitter and tough. Several varieties that are resistant to bolting are oak leaf, salad bowl, and butter crunch.

Spinach bolts under conditions similar to lettuce. For a summer crop, plant New Zealand spinach, a spinach substitute that thrives in summer heat. All spinach varieties planted in the fall seldom bolt.

Low temperatures delay the setting of fruit on a number of crops. Peppers and eggplant do not develop fruit if night temperatures fall below 58. Tomatoes will not set fruit if the night temperatures fall below 55.

Too much sun can also be harmful to some crops. Exposure to strong sunlight causes yellow, green, or purple cauliflower heads. The discolored heads have a strong flavor.

Peppers and tomatoes can suffer from sunscald. A light patch develops on the side facing the sun. The area blisters and becomes sunken and grayish white with a paper like surface. A black mold grows in the affected area, causing the fruit to rot.

Potatoes turn green when exposed to light. This occurs when the plants are not properly hilled. Green tubers are bitter and inedible. If only slightly green, they can be eaten if the green portion is removed.

Pete Hale of Sarver is a Master Gardener with the Penn State Master Gardener program.