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The P&PDL Pictures of the Week
for 21 April 2003

Eastern Tent Caterpillar

Cliff Sadof, Department of Entomology, Purdue University

Eastern tent caterpillars are a common pest of flowering fruit trees. Although they defoliate trees early in the season, the effects on plant appearance is only temporary, as trees will put on a new flush of leaves later in the spring. The health of most trees is not likely to be harmed by this temporary lack of leaves. Caterpillars spend the day in the tents, and feed at night. Control can be acheived by mechanically removing and destroying tents, or spraying an insecticide on the leaves. Please see the following link for more information: Hot News (HN-27).

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Eastern Tent Caterpillar

Photo courtesy of: Clyde Gorsuch, Clemson University

Now is the time to ID Poa annua (annual bluegrass)

Glenn Hardebeck, Turfgrass Research Agronomist, Agronomy Department, Purdue University

Poa annua is well into its spring seed head flush in Indiana. Now is the best time to differentiate Poa annua from other often-confused grasses such as Poa trivialis (roughstalk bluegrass) and creeping bentgrass. Poa annua and Poa trivialis have been considered a significant weed problem on golf courses for a number of years due to poor disease and heat stress tolerance. Now these grassy weeds, along with creeping bentgrass contamination, are increasingly becoming more of a problem in high maintenance lawns.

Proper ID is important when it comes to controlling (or attempting to control) these weedy grasses. Poa annua is an annual while Poa trivialis and creeping bentgrass are perennials, which translates to different control strategies. Perennial weedy grasses usually require one or more non-selective herbicide applications, which kills the desired grass species as well as the weedy species. Annual weedy grasses usually produce a large quantity of seeds each year that are able to germinate quickly after a total kill/seeding operation is done, especially if the seeding is not done at the optimal time for the desired grass.

So, if you have had dead patches of grass in previous summers, now is the best time to determine if the problem may be due to Poa annua. More information on these weedy grasses and their control can be found in AGRY-98-02: Control of Poa annua and Poa trivialis in Lawns and AY-11: Control of Perennial Weedy Grasses in Turf.

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Poa Annua and Poa trivialis
Creeping Bentgrass in Kentucky Bluegrass
Poa annua Spring Seedhead Flush


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Last updated: 24 April 2003/amd
The Plant & Pest Diagnostic Laboratory at Purdue University