Tag Archives: drought

Stressed out

This past week NOAA confirmed what we already knew….it was hot in July 2012. The average national temperature made it the hottest July on record and hottest month of any month on record. The real story however has been drought. Plants can dissipate heat loads if they can function normally with adequate soil moisture. Due to the heat, leaf stomates can close because of rapid water loss limiting transpirational cooling of a plant. When the plant transpires the water loss has to be made up by the root system and if adequate moisture in the soil is unavailable the plant becomes stressed out. This stress can weaken the plant, reduce yields and make it susceptible to disease or insects. Of course prolonged periods of drought will eventual move the plant from stressed to just plain dead.

Evapotranspiration map

The USDA now has a Evaporative Stress Index showing patterns of water availability and moisture stress across the U.S. Brown colored areas signify higher levels of water stress while green areas denote relatively low water stress. This map shows what my friends in Seattle have been telling me this summer. They’ve had too much rain and it has been cool while we here in the midwest have been roasting and toasting! If you would like to check out the map yourself and learn more here is the link http://hrsl.arsusda.gov/drought/index.php

Living on the “Hedge”

I remember the summer of 1988. Built an above ground pool that summer. A very hot and dry summer just like this year. I remember coming home from work one afternoon and there were so many people in the pool I wouldn’t have been able to fit a leg in the water if I tried. The summer of 2012 feels like 1988 to me.

A little water will provide “Lawn”-gevity

The lawns are just like they were then, a toasty golden brown with shrubs and trees living on the “hedge” looking stressed.

 

Trees and shrubs need your attention right now with some trickle or deep watering. This is especially true for spring plantings this year without well established root systems. Be watching for wilting or curling leaves. Some older established trees are showing leaf scorch just like they did in the summer of 1988. It’s not just the heat and drought, but wind adds to the problems increasing the rate of transpiration in foliage.

Trees showing leaf scorch

Remember the ability of your trees and shrubs to endure the stress of this season’s weather hinges in part on how healthy they were going into the season and your willingness to deep water them at the base now.

Looks like it may be too late for these Arborvitae

An impulse sprinkler or the hose nozzle you use to water your car isn’t going to work. You need to lay the hose at the base of the landscape plant and soak the soil for any beneficial effect.

Ironic that this appropriately named “Burning Bush” is showing the strain of weeks without water

 

 

 

 

 

 

 

I’ve had a lot of people lately ask me if their lawn is going to survive the heat and drought. Turfgrass dormancy is a survival mechanism allowing survival up to 4-8 weeks without irrigation or precipitation without significant thinning upon recovery from dormancy. This would be under ideal conditions of no traffic, good sub or parent soil, moderate temperatures, minimal root competition from trees, etc. Survival can be affected by species, age, shade, maintenance, the quality of feeding you have done in the past, the deck height on the mower, traffic, heatand other factors. Raise the deck on your mower and if you can, park the mower until the drought is over.

 

 

A shaggy lawn is better than a scalped stressed turf. Remember that dormancy is reversible but death is not. If the lawn goes too long without any water or if it was unhealthy and stressed going into the drought the roots my die causing thinning of the turf. Cool season turf can survive summer dormancy but cannot survive root death.

Cool season lawn dormancy. Remember dormancy is reversible, death is not.

Turfgrasses that are trafficked during drought conditions must be irrigated regularly to maintain performance and prevent widespread turf damage. Lawn areas established in spring or previous fall should be irrigated because they have not yet developed extensive root systems.

Check irrigation systems for improperly aimed sprinklers, defective heads and evenness of distribution, etc. Water in the early morning hours to improve efficiency because of less evaporation from sun and wind. Watering at sunset encourages disease issues.

Limit traffic on your lawn (including mowing) to minimize crushing of the turfgrass leaves and crowns. Avoid the temptation to apply herbicides even though weeds become more obvious in a dormant lawn because they may be the only thing left that is green! Wait until fall to control lawn weeds, a perfect time for weed control.
Remember the fall season is a perfect time for overseeding and feeding thinned lawns. Turf establishment in Michigan is best done between August 15 and October 15 so don’t lose your “composture” if things are looking bleak right now. Your window of opportunity to improve the green green grass of home is coming soon!