Tips and resources for farmers and gardeners
A dry winter, minimal spring rains, record high temperatures and low summer precipitation is putting extreme stress on woody plants in many areas of the country this summer. The stress increases susceptibility to insects and disease.
Trees and shrubs should be thoroughly watered if they begin to show signs of leaf wilt, discoloration or drying, especially at leaf edges.
Newly planted trees are particularly at risk during prolonged dry periods, but even trees that have survived harsh conditions in the past can decline or even die from extended drought and heat.
To check soil moisture in a tree's root zone, push a long screwdriver into the soil a foot or two out from the trunk. If the ground is dry and in need of watering it typically is difficult to push the screwdriver in more than a few inches.
Five gallon buckets with holes can also be used to slow-irrigate the soil under trees.
The soil type does affect watering. Sandy soils have to be watered more frequently. Clay soils can be hard to re-hydrate once they dry out but will retain moisture longer.
It is also important to have 2-3 inches of mulch under trees to conserve moisture and insulate the soil from high temperatures. Unlike turfgrass, mulch doesn't compete with the tree for nutrients and moisture.
Some symptoms of drought - stunted or distorted foliage - are similar in appearance to herbicide damage. High temperatures can cause herbicides like 2,4-D to volatize and change from liquid to gas. As a result, the herbicide doesn't bind to soil particles but rises and spreads to trees and shrubs where it damages and distorts the foliage.
Applying herbicides and/or fertilizing during extreme heat is more likely to cause damage to plants than to provide assistance.
Source: Amy Seiler, Nebraska Forest Service,
Oak Tree, Sunrise
by Ansel Adams