Gary Y. Gao, Joseph F. Boggs, Pamela J. Bennett, Jane C. Martin, David E. Dyke, Joseph W. Rimelspach, John R. Street, William E. Pound, Amy K. Stone, Erik A. Draper, and James A. Chatfield
The year of 1999 was very stressful to lawns in Ohio due to extended severe drought conditions. This article is a compilation of cultural and disease problems of turf, as well as recommendations offered in the weekly Buckeye Yard and Garden Line from April to October in 1999.
Many homeowners noticed areas in the lawn that were not greening up in spring. It was probably caused by the dry fall of 1998. Many non-irrigated lawns on hard, compacted soils and with southern exposures suffered considerable stress and decline. Kentucky bluegrass lawns with dead spots no larger than two to four inches in diameter could be revived with a regular spring application of nitrogen. Re-seeding was recommended for many areas.
During the week of April 23, extensive yellow patches were observed in some lawns. The yellow mottling was due to scalping, caused by setting the lawn mower cutting height too low. Grasses, especially tall fescue and perennial ryegrass, grew very rapidly. When cut too short, too much photosynthetic tissue is removed, and the remaining tissue appears yellow. While the recommended mowing heights for different kinds of grasses vary, there is an excellent rule of thumb to follow when mowing a lawn – the 1/3 rule. That is, no more than 1/3 of the total leaf surface should be removed at any one mowing.
Many homeowners believe that moss can out compete turfgrass when, in fact, moss grows where environmental conditions challenge turf growth and establishment. Generally, moss thrives in areas with poor drainage, insufficient sunlight, inadequate air circulation, low fertility, low or high pH, compacted soil, or any combination of these conditions.
Although several materials are labeled for moss control, they are considered a temporary solution. Moss can be successfully managed by correcting conditions that challenge turf establishment and growth. Nutrient and pH imbalances can be corrected by using a soil test and proper fertilization. Soil compaction may be alleviated by core aeration. Insufficient sunlight can be corrected by planting shade-tolerant grasses, such as fine fescue, or shade-loving ground covers, such as English ivy or pachysandra. Inadequate air circulation can be improved by thinning lower tree branches.
Heavy seedhead production was observed on Kentucky bluegrass in mid-May. Homeowners can either mow high to hide seed stalks or mow low one time to remove most seedheads and then resume regular mowing heights. For those wondering why some Kentucky bluegrasses are heavy seedhead producers, the main reason is economics. Turfgrass breeders select grasses for many important traits, including higher seed yields for seed production. Unfortunately, in a lawn situation, the ability to yield high numbers of seed is much less desirable.
During the week of May 27, it was advised that summer turf management practices begin, due to a lack of rain. Those practices included raising mowing heights to 2.5 to 3.0 inches for all turfgrasses. Also, the last spring fertilization should have been applied (3/4 to 1 lb. of actual nitrogen per 1,000 square feet) for turf on a high maintenance program. Using a slow release form of nitrogen for at least 30% to 50% of the nitrogen can help avoid possible fertilizer burn.
By late June, many lawns across Ohio were of pretty poor quality due to continuing drought conditions. The various turfgrasses responded to drought stress differently, i.e., fine fescue is less drought tolerant than tall fescue. Management practices were provided to maintain turfgrass quality under drought conditions. Keep mower blades sharp; raise mowing height to 2.5 to 3.0 inches; do not mow during the heat of the day. Do not fertilize stressed grass and if fertilizer must be applied, then the turf must be watered thoroughly. Do not apply herbicides if lawns are stressed; there is greater potential for turf damage and herbicide efficacy will decrease. If irrigation is a must, prioritize lawn areas so as to maximize water use efficiency (e.g., front of the house and high traffic areas receive the most water).
Supplemental irrigation was recommended in July to help minimize direct drought injury to turfgrass. About one inch of water applied every six to eight weeks to the lawn was recommended. This minimal watering did not turn the turf green, or promote disease development if done during the early morning hours. Instead, this small amount of water helped keep turfgrass crowns and roots alive. This was critical to allow turf to recover from drought conditions.
A sample of crown anthracnose on annual Kentucky bluegrass was sent to the Ohio State University C. Wayne Ellett Plant and Pest Diagnostic Clinic during the third week of June. Normally, anthracnose infects grass leaf blades. The symptoms were irregular-shaped patches from two inches to 10 ft. in diameter. Initially, areas were a reddish-brown. As the disease progressed, color faded to light yellowish tan. The pathogen can also infect crowns of turfgrasses and kill them, especially where soil drainage is poor. Annual bluegrasses infected with crown anthracnose did not recover. This disease can also attack bentgrasses.
For much of Ohio, August 15 to September 15 is considered ideal or optimal for re-seeding areas killed by drought or other causes, such as bluegrass billbug.
Early September until mid-October is ideal for lawn seeding and renovation in southern and central Ohio. In northern Ohio, this task should be completed by mid-September for best results. These recommendations are for optimum results in germination and winter hardiness of turf. Turf can be seeded later in the fall, but the risk of winter injury increases as seeding and germination is delayed.
Several steps are important in assuring the success of fall turf renovation. Those steps include turfgrass cultivar selection, soil preparation, and irrigation.
Recommended turfgrass cultivars can be found in OSU Extension Fact Sheet, HYG-4027, Turfgrass Cultivar Selection. Refer to the National Turfgrass Evaluation Program web site at http://www.ntep.org/tables.htm for the latest turfgrass cultivar performance ratings. It is important to establish good seed to soil contact by raking, vertical mowing, or dethatching prior to seeding. Slit-seeding was also recommended. Core-cultivation could be also used, but does not usually produce enough soil exposure to be used alone. A starter fertilizer at the time of reseeding is also recommended. Irrigation was also recommended since it did not rain much in September and October in many parts of Ohio.
September is the perfect time to apply the first fall fertilizer application on lawns. The next application should be made in late October or November. It is also noted that if the lawn is extremely dry, it would be helpful if irrigation was applied, but it is not essential. Of course, if the lawn receives adequate water along with this fertilization, recovery could be good in many cases. Research has shown that under normal conditions in Ohio, fall fertilization enhances turfgrass growth, quality, and recovery from summer stress. Its impact carries over into spring and is a very important component of any turfgrass management program.
Moisture from fog, dew, and cooler temperatures in September was favorable for the development of many cool-season pathogens in 1999. Dollar spot, red thread, leaf spot, and rust were the observed fungal diseases this fall.
There were many inquiries about the suitability of buffalograss for Ohio lawns, since this grass is very drought tolerant. Several excellent buffalograss cultivars have been developed by researchers with the University of Nebraska for the Central Plains. However, buffalograss has limited adaptability, if any, for the weather conditions commonly experienced in Ohio.
Buffalograss (Buchloe dactyloides) is a species that has prospered on the Great Plains for centuries. Buffalograss is a warm-season grass. There are several undesirable characteristics associated with buffalograss, even with newer selections of this species. The first problem is weed invasion, since buffalograss grows very slowly. The second problem is poor tolerance of buffalograss to typical wet springs in Ohio. Another problem is poor lawn quality since buffalograss spreads by stolons. Last but not least, buffalograss is similar to zoysiagrass, another warm-season grass, which turns brown very quickly when cold weather hits. In brief, buffalograss is not suited for Ohio lawns.