[Pythium & Rhizoctonia spp.]
Damping off is a seedling disease that may develop before or after the emergence of turfgrass seedlings. Sparse emergence of seedlings and slow establishment occurs when seeds are infected prior to emergence. When the disease develops after emergence, seedlings initially appear flaccid and twisted as if suffering from wilt. The seedlings continue to decline, turning dark in color and greasy in appearance, and then quickly disintegrate to leave areas of bare soil. Damping off initially develops in localized spots, but the disease often spreads rapidly to injure large areas. In severe cases, tufts of mycelium may be observed in affected areas when the leaves are wet.
Host Grass Species
bentgrass, bluegrasses, fescues, ryegrasses
Month(s) with symptoms
spots, patches (4 to 12 inches), or irregular distribution across turf stand
Foliar Symptoms - Location/Shape
blighting of entire leaves
Foliar Symptoms - Color
tan, brown, or black
roots, stolons, rhizomes, and/or crowns dark brown or black
mycelium or none
Note: Still not sure if this is the right disease? The Turfgrass Disease Identification program may be helpful. Or consult the experts at the Turf Diagnostics Lab. Check the TurfFiles glossary for definitions of unfamiliar terms.
FACTORS AFFECTING DISEASE DEVELOPMENT
Turfgrasses are most susceptible to damping off during germination and seedling emergence. After emergence, the turf gradually becomes resistant to the disease as it matures. Damping off is most severe when temperatures or light levels are unfavorable for seedling growth. Pythium causes the majority of damping off problems during warm or hot weather, whereas Rhizoctonia is more prevalent during cool weather.
The disease is encouraged by excessive nitrogen fertility and extended periods of leaf wetness. High seeding rates encourage damping off by producing dense populations of seedlings that mature more slowly and remain wet for extended periods of time.
Use recommended seeding rates, which are designed to speed the maturation of seedlings and minimize the window of time when they are susceptible to damping off. Apply a high phosphorous (P) starter fertilizer at the time of seeding to provide 1 pound of P per 1,000 square feet. To encourage rapid germination, water lightly and frequently to keep the seedbed moist but not saturated. As the seedlings emerge and develop a root system, gradually reduce the irrigation frequency, and ensure that the seedling leaves dry completely in between irrigation cycles. Apply a thin layer of straw or other mulching material to hold in moisture, but do not over-apply as this will retain too much moisture and increase the risk of damping off. A second fertilizer application is typically made around the time of the first mowing, but do not apply more that 0.5 pound of readily available nitrogen per 1,000 square feet. Do not attempt to establish turfgrasses in low-lying, wet areas where damping off is most severe.
Fungicides are available for control of damping off, and may be applied as seed-treatments or directly to the seedbed. If damping off is observed, submit a sample to a diagnostic lab for accurate diagnosis because different fungicides are needed for control of Pythium and Rhizoctonia species. Note that fungicides labeled for damping off only have activity against Pythium species. The fungicides labeled for brown patch are needed to provide effective control of Rhizoctonia damping off.
Resistance Risk (2)
propamocarb + fluopicolide**
benzamide + carbamate
Fenox, Mefenoxam 2, Mefenoxam 2 AQ, Quell, Subdue
fluoxastrobin + myclobutanil
DMI + QoI
Disarm, Disarm G
** Not for application to residential lawns.
excellent control when conditions are highly favorable for disease development
good control when disease pressure is high, or excellent control when disease pressure is moderate
good control when disease pressure is moderate, excellent control when disease pressure is low
good control when disease pressure is low
does not provide adequate control under any conditions
cannot be rated due to insufficient data
Rotating and tank-mixing not necessary, but recommended to avoid potential side effects from continuous use of same chemical class.
Rotate to different chemical class after 3-4 applications; tank-mixing not necessary.
Rotate to different chemical class after 2-3 applications; tank-mixing not necessary.
Rotate to different chemical class after 1-2 applications; tank-mixing not necessary.
Rotate to different chemical class after 1-2 applications; tank-mixing with low or moderate risk product recommended.
Rotate to different chemical class after EVERY application; tank-mix with low or moderate risk product for EVERY application.
Continual use of fungicides with similar control mechanisms (modes of action) can result in fungi that are resistant to some chemicals. Poor or ineffective disease control can be expected when this occurs. Managers can reduce the chances of this happening by mixing or alternating fungicides belonging to different chemical classes.
Recommendations of specific chemicals are based upon information on the manufacturer's label and performance in a limited number of trials. Because environmental conditions and methods of application may vary widely, performance of the chemical will not always conform to the safety and pest control standards indicated by experimental data. When more than one brand name exists for an agricultural chemical, the name of brand that first came onto the market is listed first. Otherwise, brand names are listed in alphabetical order. The order in which brand names are given is not an indication of a recommendation or criticism.
Recommendations for the use of agricultural chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services does not imply endorsement by North Carolina State University or discrimination against similar products or services not mentioned. Other brand names may be labeled for use on turfgrasses. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact your county's Cooperative Extension agent.
© North Carolina State University. This information sheet was prepared by Lane P. Tredway, Gail G. Wilkerson, Bridget R. Lassiter, Jenifer J. Reynolds, and Gregory S. Buol. Departments of Plant Pathology and Crop Science, College of Agriculture & Life Sciences, North Carolina State University. Prepared March 7, 2011. Available on-line at www.turffiles.ncsu.edu. This publication was made possible through a grant provided by the Center for Turfgrass Environmental Research & Education (CENTERE) whose purpose is to support worthwhile projects that will benefit both the private sector and the public, and protect the environment.