Q&A WITH Brian Aynardi Ph.D.

Advertisement

1. What are the symptoms of Pythium root disease?

Pythium root rot occurs on creeping bentgrass, mixed bentgrass/Poa Annua, and ultradwarf bermudagrass putting greens. Often found in push-up greens that hold a lot of moisture, Pythium root rot results in orange or bronze irregular patches, as well as brown, "sizzled," shortened roots that can’t properly translocate water and nutrients.

Pythium root dysfunction occurs almost exclusively on newly established creeping bentgrass putting greens. Plants with Pythium root dysfunction lack root hairs but may otherwise appear somewhat healthy. Stand symptoms appear more as off-color circular patches.

2. How to control Pythium root diseases?

A preventive fungicide program is essential with any type of root-infecting pathogen, as these Pythium species damage roots before above ground symptoms manifest themselves. Initiate preventive applications when soil temperatures are ~60°F at the 2-inch depth and continue through the summer growing months.

Segway® Fungicide SC has been recognized as the industry gold standard for Pythium control for nearly a decade, and should be used in rotation with other products that control root Pythium pathogens. A 14-day alternating program of Segway (or Union® Fungicide SC, a premix product of cyazofamid + azoxystrobin) and Serata™ Fungicide, a new product from FMC, has demonstrated unparalleled Pythium root disease control in university research trials and on golf courses.

Fortunately, neither of these Pythium diseases typically result in death of a putting surface, and curative fungicide applications of Segway (cyazofamid) or Union (cyazofamid + azoxystrobin) fungicide result in recovery that is evident within 10-14 days after application.

3. What do Pythium blight symptoms look like?

Pythium blight is one of the most feared of all diseases in the turf industry, as it can kill large areas of turf quickly. Pythium blight often starts in small, dark patches about the size of a human hand, and is associated with aerial mycelia when the pathogen is active. Infected areas are bronze in color, and usually move in irregular patterns with topography due to the pathogen’s affinity for water. Symptoms on bermudagrass include black lesions when the disease begins to develop. Scout for Pythium blight in areas where there is little to no air circulation when conducive environmental conditions exist.

4. How to control Pythium blight?

Preventive applications for Pythium blight are imperative, and Segway is the premier Pythium blight control product. Because Pythium blight affects the foliage, a carrier volume of 2 gal./1,000 sq. ft. is ideal. As with root Pythiums, control of foliar blight is best achieved on shorter intervals, such as 14-days.

Pythium blight occurs on cool-season grass when daytime temperatures exceed 85F, nighttime temperatures exceed 65F, and relative humidity is greater than 90% for 14 consecutive hours. Pythium blight does not require the same strict conditions to develop on bermudagrass.

On that host species, Pythium blight occurs when significant periods of rain, high humidity and clouds exist, especially during the shoulder seasons or during tropical storms, but does not require specific temperature parameters.

5. How to control Pythium damping off?

Damping-off is a disease of emerging or newly emerged seedlings. There are no specific environmental conditions associated with damping-off. However, due to the potential for seedlings to be killed, a preventive application at the time of seeding or at seedling emergence is critical. Apply Segway or Union fungicide in sufficient carrier volume (2 gal. carrier/1,000 sq. ft.) and repeat applications on newly emerged grass as needed.

Serata™ is a trademark of FMC Corporation.