Extension News

Ask the ISU Experts

Note to media editors:

Got gardening questions? Contact the Hortline at (515) 294-3108 (Monday-Friday; 10 a.m. - 12 noon  and 1-4:30 p.m.) or send an e-mail to hortline@iastate.edu. For more gardening information visit us at Yard and Garden Online at www.yardandgarden.extension.iastate.edu



What is the proper way to water a lawn? 
Most lawns in Iowa require approximately 1 to 1.5 inches of water per week. When watering the lawn, apply this amount in a single application or possibly two applications three or four days apart.  Avoid frequent, light applications of water, which promote shallow rooting and lush growth.  Lush, shallow-rooted turfgrass is less drought tolerant. It is also more susceptible to pest problems.  To determine the amount of water applied by a sprinkler, place two or three rain gauges within the spray pattern. 

Early morning (5-9 a.m.) is the best time to water a lawn. A morning application allows the water to soak deeply into the soil with little water lost to evaporation. When watering is completed, the turfgrass foliage dries quickly. Watering at mid-day is less efficient because of rapid evaporation and strong winds may cause uneven water distribution. Strong, mid-day winds may also carry water onto driveways, sidewalks, or streets, wasting considerable amounts of water. Watering lawns in late afternoon or evening may increase disease problems. 

I have several rows of grapevines. What would be a good cover crop between rows? 
Kentucky bluegrass is an excellent choice. Bluegrass provides good cover, yet is less competitive than other cover crops. Late summer (mid-August to mid-September) is the best time to establish bluegrass by seed. Do not sow bluegrass seed underneath the trellis. The area directly beneath the trellis should be kept free of grass and other vegetation. This clean, plant-free area should be 3 feet wide. Maintain the bluegrass at a height of 3 to 3.5 inches. Leave the grass clippings on the area. 

The leaves on my red-twigged dogwoods are spotted and beginning to fall off.  Why? 
The spotting and premature leaf drop on your dogwoods is probably due to Septoria leaf spot. Septoria leaf spot is a common fungal disease of dogwoods in Iowa. The disease typically causes irregularly shaped grayish spots with dark purple or reddish borders. Heavily infected leaves often drop prematurely. Wet spring weather favors Septoria leaf spot development. 

Fortunately, Septoria leaf spot will not destroy the dogwoods. The damage is mainly aesthetic. The heavily spotted foliage is not very attractive. 

The severity of Septoria leaf spot in future years can be reduced by raking up and disposing of the infected leaves on the ground. It is possible to control Septoria leaf spot with three or four fungicide applications in spring. However, most home gardeners choose not to apply fungicides as the damage is mainly aesthetic. 


Contacts :

Richard Jauron, Horticulture, (515) 294-1871, rjauron@iastate.edu

Jean McGuire, Extension Communications and Marketing, (515) 294-7033, jmcguire@iastate.edu