Not much going on disease-wise in the mid-Atlantic in recent weeks. I thought the heavy rain events from October 1 to 4 (about 6.5” on Delmarva Coast) would surly have brought on dollar spot- historically a major disease problem at this time of year. The rains were cool and not warm, and ushered in cool air temperatures, which likely had a big effect on pathogen activity. Regardless, I have seen some dollar spot, brown patch and huge numbers of mushrooms. Etiolated tiller syndrome (ETS) and rust are about the only diseases to have some degree of frequency.
Etiolated tiller syndrome, also referred to as ‘mad tiller disease’ or ‘ghost disease’, is commonplace in annual bluegrass, creeping bentgrass and perennial ryegrass during cool, wet and overcast periods in spring and autumn, but can develop during rainy and overcast weather in summer. A similar etiolation of leaves is a prominent symptom of bacterial wilt disease in annual bluegrass. The cause of ETS in bentgrass and ryegrass is unknown, but some have suggested that gibberellin-producing fungi (Fusarium spp.) or bacteria (Xanthomonas spp.) as possible causal agents. A similar malady, with a “buggy whip” symptom not unlike ETS, has been reported in zoysiagrass, which is caused by a very small “eriophyid” mite.
Others have suggested that ETS is an environmentally-induced physiological disorder or is caused by plant growth regulators (PGR), or maybe biostimulants containing gibberellic acid. The malady, however, commonly is observed in turfs where no PGR’s or biostimulants have been applied. Symptoms of ETS include rapid elongation (i.e., etiolated growth) of the youngest leaf through the bud shoot, which is distinctively lime-green or yellow. Except during periods of extreme heat stress, affected plants do not die, but there can be some tip dieback of leaves. Etiolated leaves are not easily removed by mowing. This phenomenon is worse in approaches, collars and clean up areas of greens. Superintendents who attempts to mow more aggressively to remove etiolated leaves, may experience wear or mechanical damage. There are no documented control measures for ETS. Anecdotally, an application of Primo MAXX in combination with a DMI/SI fungicide (e.g. Banner MAXX, Bayleton, Triton, Tourney, Torque, and others) may reduce, but does not eliminate leaf etiolation. The bottom line is live with it. Most golfers could care less!
Rust (several Puccinia spp.) mostly is a problem in Kentucky bluegrass and perennial ryegrass, and sometimes tall fescue grown in shady areas during late summer and autumn. If there is an extended period of overcast weather, however, rust can debilitate and thin turf in open areas. Rust gives turf a yellow or orange appearance from a standing positon. On close inspection, yellow, orange or brick-red-colored pustules can be seen on leaves. Huge numbers of spores are produced within each powdery pustule, which spread the pathogen. Sporulation can be so massive that spores turn shoes a rust or yellow color. Rusts are highly sophisticated obligate parasites that live and reproduce in living tissues only. What makes rusts so sophisticated is that they have a complicated lifecycle, and being obligate parasites, they do not usually kill turf since the fungus requires a living plant tissue within which to survive. During most other times of year rust-infected plants appear amazingly healthy. Rust is disfiguring, weakens plants and predisposing them to other stresses when sporulating. Rust causes thinning of the stand, thus inviting weed invasion, especially winter annuals. Rust is easily controlled with a single application of a DMI/SI fungicide (e.g. Banner MAXX, Bayleton, Triton, Tourney, Torque, and others).