• Notes From The Field

Rapid Blight Hits SW Golf Course Turf

Tuesday, September 9, 2008

by Todd Burkdoll

Rapid Blight conditions ripe as the Southwest enters fall/ winter months

Rapid Blight is not a new disease. It's been around for a while and affects the Southwestern states particularly in the fall/winter months of September, October and November. Rapid Blight occurs predominantly because of poor quality irrigation water with high salinity.

Conditions favoring this disease are usually seen in the late summer and early fall as salt build up in the soil becomes elevated due to irrigation water with high sodium content and/or naturally occurring high sodic soils. Rapid Blight is characteristic of its name, and infection is usually very devastating to turf greens and fairways if left untreated. The disease causes rapid decline and death of cool season grasses, thus in Bermuda greens or fairways, which are over seeded for the winter dormant period, the disease can be devastating.



Rapid Blight, courtesy of Dr. Bruce Martin, Clemson University.

Prevention program essential for Southwest golf courses with high saline levels in soil



Rapid Blight is not a fungus—it's an organism more closely associated with marine diatoms thus the affinity for high sodium levels. When the disease hits, there will be a die back of the turf. Rapid Blight reproduces at a very high rate when conditions are right, and once it hits, there's virtually no curative measures that can be taken. In order to avoid this annual pest, golf course superintendents must focus on prevention.

When you see the sodium levels and electrical conductivity rising on your soil and irrigation charts, it's time begin your prevention program. It is helpful to evaluate records from past years, and work those seasonal indicators into your buying choices and spray plan.

Preventative application using Insignia® Fungicide protects turf from Rapid Blight

Insignia® fungicide has a unique activity on Rapid Blight. The active ingredient, pyraclostrobin is locally systemic, moving both upward and downward to a limited degree, to protect unsprayed portions of the leaf. In addition, pyraclostrobin will move from the top to the bottom of the leaf (translaminar movement), so Insignia applied to the top of the foliage will give protection to the underside as well.

University of Arizona researcher, Dr. Mary Olsen, is drafting a biology-based essay on the mode of action that is able to kill Rapid Blight and other marine organisms.

My prevention program recommendations are:

Apply Insignia® fungicide with a No. 4 contact material as part of a prevention program.

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