Hot weather has a way of pointing out certain garden problems. For instance, a few blistering days usually shows you which plants are not adapted to hot weather, as well as which plants you haven't been watering properly. But while wilting and leaf scorching are plant symptoms that most gardeners can identify as heat related, some symptoms are much more subtle.

A good example is blossom-end rot of tomatoes, a problem that many gardeners encounter, but one which few associate with hot weather. Blossom-end rot appears as a leathery, water-soaked spot at or near the blossom scar of green fruits. The skin remains unbroken because it is the tissues beneath that have dried out and collapsed. The disorder is caused by changes in soil moisture or sudden water shortages. It is most severe when rapidly growing plants in well-watered soils are suddenly exposed to a hot, dry spell. The best way to prevent blossom-end rot is to keep your plants well watered. Mulch your plants to help conserve moisture and keep the soil cool. You need to correct problems relating to poor soil drainage before you plant tomatoes, since a lack of aeration contributes to the problem.

Another example of a hot weather problem is a disorder called pit burn, which occurs in the fruit of some apricot varieties. Pit burn affects apricots between the time the fruit begins to lose its grass green color, to about the time it's ripe enough to pick. After a few days in the high 90's or above, pit burn may begin to show up, especially in a heat intolerant variety like Blenheim (Royal). The first evidence of the disorder is a softening of the flesh around the pit, as if the pit had been heated, causing the flesh in the interior to ripen faster than the exterior. The soft area around the pit turns brown in a few days, but there is no evidence of trouble on the outside of the fruit. When cut, fruit in the late stages of pit burn often are affected by one or more of the rots that attack ripe fruit.

Because pit burn is caused by hot weather, there is little you can do to prevent pit burn in some varieties. Keeping the soil moist during the time the fruit is maturing may help somewhat. Use moisture-conserving mulches whenever possible. If you are planning to plant an apricot tree, consider a variety like Tilton, which tolerates the heat better.

While on the topic of fruit trees, it's important to remember that next year's bloom and crop are very dependent on how you water your tree this summer. Continue to provide your trees with periodic deep irrigations through late summer. Drought-stressed trees will bloom poorly and set poor crops next spring.