Hort Shorts

Tomato Leaf Roll
The edges of leaflets roll inward toward the mid-vein and the leaflet is somewhat leathery to the touch. This is caused by a fluctuation in moisture in the root zone, going from ample moisture to a shortage or by excessive pruning. Fortunately this problem does not adversely affect the production of tomatoes. Leaves remain green and hang on the plant, though affected leaflets do not unroll. If you are irrigating, try to keep the soil moisture level consistent and account for rainfall when irrigating. Some tomato varieties are more susceptible to leaf roll than others, such as Beefsteak, Big Boy and Floramerica.

Crabgrass Prevalent
Crabgrass has become quite noticeable and abundant in some lawns, particularly along driveways and sidewalks, areas where lawn grasses are usually stressed. The hot, moist conditions in July contributed to it’s germination and rapid growth. However, there is no herbicide treatment for crabgrass now. Remember, it is an annual grass, and will die out with a hard freeze this fall. For now, dig plants, keep it mowed off or clip off the seed heads to eliminate seed set and a further buildup of seed in the soil.

White Grubs Update
Adult annual white grubs (masked chafers) emerged in central Illinois during the last week of June and were reported in northern Illinois a few days earlier. Checking beetle number around lights at about 10:30 p.m. will provide insight on both the northern and southern masked chafer emergence in your area. The number of adult Japanese beetles present during the day on landscape plants will give you an idea of their numbers.

The relative number of these adults plus the soil moisture will provide you with the information you need for preventative white grub treatments in turf. All three species feed in the larval stage as white grubs on the roots of turfgrass. The adults are attracted to damp soil, which they tunnel into to lay their eggs.

If your area has received enough rainfall so that non-irrigated grass is green with moist soil and the beetle flight is not unusually heavy, then it is likely that grubs will be present in damaging numbers only in small areas, which are conducive to spot treatments with quick-acting insecticides in August. If only irrigated turf is very green with moist soil and the adult flight is normal to heavy, then those irrigated turf areas will likely have heavy grub numbers. These are the turf areas where imidicloprid (Merit) or halo—fenozide (Mach 2, Grubex) should be applied by the end of this month to prevent grub damage in the second half of August. Many areas of the state have enough soil moisture that white grubs will not be a problem this year. However, that can reverse itself if the rains stop and temperatures are high for the next couple of weeks and unwatered turf goes dormant.

August 2000
EPA Ends Over-the-Counter Sale of Dursban | Root Rot | Now is the Time for Overseeding | Asian Longhorned Beetle War | Lawn Care Calendar | Bug Bites: Late Summer Tree Insects | Cybergarden Sites | Hort Shorts | Hort Tips | Locally Grown: Small Tomato Time | We All Scream for Ice Cream | The Herb Garden: Drying Herbs | Health & Household Tips | Did You Know?

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