From Terre Haute to Rockville, Indiana up to Perrysville & Covington, temperatures are now hitting 100°. Interestingly with that 99.8 at Covington, the dew point is incredibly low at 48°, bringing the relative humidity down to 17%.
At WLFI, our 96.6° is accompanied by a 40° dew point, giving us a relative humidity value of 14%.
Drought issues continue in our landscapes and urban forests.
Lindsey Purcell, Urban forestry Specialist, Purdue University
“Historically, a drought like the Dust Bowl would happen every 100 years, but what we’ve found is that modern droughts are shorter and can be more severe,” according to the journal Agricultural and Forest Meteorology. “Historic data observed showed that those trends are expected to produce conditions in which droughts would be short, harsh and costly, but rare.”
Indiana landscapes are suffering from the worst drought conditions in over 100 years and trees are dying. This seemingly endless pattern of dry weather are affecting crops and plants of all kinds, so, now what? With a little help from us, we can salvage and save trees from anticipated problems next year and be prepared for the future.
Drought can have a major impact on tree health and survival. The effect slows and reduces growth. It reduces carbohydrate production, which significantly lowers energy reserves, and production of defense chemicals in the tree. If drought is severe enough or lasts long enough it also can cause death to all or parts of the tree.
In most situations, prolonged dry weather weakens trees and they become more susceptible to pests, which normally cannot invade a healthy tree. These pathogens enter, weaken and kill all or part of the tree, depending on how badly the tree is predisposed to a weakened state. At this point in the environmentally induced decline we can expect some permanent damage to our urban forests.
A “biological lag” effect is common in trees where environmental conditions during the year of bud formation controls shoot length and expansion. Drought during the year of bud formation decreases the number of new leaves formed in the bud and new stem segments. Drought then influences the number of leaves, size of leaves, and twig extension the following year when those buds expand.
The results of prolonged dry conditions may not inhibit the first growth flush, but may decrease the number of stem units formed in the new bud that will expand during the second (or third, etc.) flush of growth. If drought continues, all growth flushes will be affected. Thus, tree growth next year will be atypical and again, create predisposed conditions to diseases and insects if not monitored and managed properly.
Always protect tree trunks, especially young trees, from mechanical damage such as string trimmers, lawn mowers and other equipment. Preventing damage to the bark and wood at the base of the tree maintains a continuous ring of water and food transporting tissues.
Reduce competition for available moisture with other plant materials such as turf, shrubs and groundcovers, where feasible, by removing plants and adding mulch. Maintain an adequate mulch layer throughout the year. Add extended mulch beds and rings under the drip line of the tree canopy to protect those fine “feeder” roots from drying out.
Water trees, whenever rainfall is insufficient for extended periods of two weeks or more, Especially on newly planted trees and those less established. A proven recommendation is to use the 5 + 5 rule. Which is to provide 5 gallons of water plus 5 gallons for every diameter inch of tree trunk. This should provide plenty of water to help the tree during times of inadequate moisture.
For mature and well-established trees, a good rule is to provide an inch of supplemental water every two week or so to keep leaves turgid. To determine the amount of irrigation, place a tuna can or similar catch device to measure the amount of irrigation provided to the root zone of the tree planting space. It is advisable to water plants though the fall until the ground is frozen; maintaining adequate moisture to survive the winter months and allow the trees to be ready for spring growth.