Heat Related Problems and Solutions


Summer has finally arrived with its soaring temperatures along the
Central Coast.  Reducing heat related problems in the garden starts with the basics.

·         Choose plant materials that are heat tolerant.

·         When hot temperatures are predicted, irrigate your lawns and garden before the temperatures rise.

·         Use mulches to reduce evaporation of water from the soil surface and to keep soil temperatures cool

Although good soil moisture can help plants to survive high temperatures, some damage may still occur.

·         Your garden may give you obvious signs that watering is needed.  Leaving footprints in your lawn is a sign to irrigate.  Symptoms of heat stress may not be as obvious.  Tomatoes exposed to the hot sun may turn light brown and become leathery on the exposed side.  This problem can be reduced, but not relieved altogether, by adequate watering.

·         Leaf Scorch occurs in maple, chestnut, beech, walnut and other assorted trees during high temperatures and drying winds.  Scattered areas in the leaf, between the veins or along the margins turn light or dark brown, with all the leaves on a branch affected uniformly.  The canopy of the tree looks scorched; leaves may dry and fall.  Lack of fruiting bodies distinguishes scorch from a fungus leaf blotch.  Sun scald, sometimes called sun burn is caused by a combination of too much light and heat and insufficient moisture.  Trees with thin, smooth bark, and newly planted trees are most susceptible.  Mature trees can also sun scald when the trunk or branches are suddenly exposed to the sun after vigorous pruning or when neighboring trees are removed.  Paint the exposed trunk and scaffold branches with white interior water based paint, diluted 50% with water, or commercial whitewash to prevent sunburn.

·         Tip burn is common in lettuce and potatoes and is evidenced by marginal browning of the leaves and small brown or bleached spots in tissues near larger veins.  Regular irrigation and moderate fertilization reduces tip burn.  A more effective solution is to grow varieties resistant to heat.

University of California Cooperative Extension Master Gardener Volunteers can provide additional gardening information upon request .Call the San Luis Obispo office at 781-5939 on Mondays and Thursdays from 1 to 5 PM.  You may also call the Paso Robles office at 237-3100 on Wednesdays from 9 AM to 12 PM.  The San Luis Obispo Master Gardeners website is at http://groups.ucanr.org/slomg/.  Questions can be e-mailed to: mgsanluisobispo@ucdavis.edu.