Take-all Root Rot on Southern Turfgrasses

This disease affects all species and varieties of southern turfgrasses including St. Augustinegrass, Bahiagrass, Cenetpedegrass, Zoysiagrass and Bermudagrass. The pathogen is naturally present on warm-season turfgrass roots. High rainfall and stressed turfgrass trigger the disease, and it is therefore observed during the summer and early fall months when Florida receives the majority of its rainfall. Any stress placed on the turfgrass can encourage or worsen the disease.

St, Augustine Roots Damaged by
TARR Fungus

This is a root rot disease. Because the roots are affected, they are not able to efficiently obtain water or nutrients from the soil, nor are they able to store the products of photosynthesis. Symptoms observed on the leaves are the result of pathogen activity on the root system. The fungus does not attack leaves.

Initial symptoms aboveground are irregular, yellow (chlorotic) or light green patches ranging in diameter from a few inches to a few feet. Roots are initially thin and off-white in color with isolated black lesions. Eventually, roots become very short, black, and rotted. Stolons and rhizomes may have black lesions and, under severe disease conditions, begin to rot. Entire plants may die, resulting in irregular patches of thinning grass, and if the rot is not controlled, bare patches may develop.



St. Augustinegrass Damaged by TARR Fungus

To minimize damage to the turf, stress factors need to be minimized by following Green Industries Best Management Practices recommendations (GIBMP). The turfgrass must be mowed at the correct height during the summer. Turfgrass should be mowed as frequently as necessary so that only one third of the leaf tissue is removed during any one mowing event. Scalping the grass damages the growing point.

Empire Zoysiagrass Damaged by TARR Fungus

Balance nitrogen applications with equal amounts of potassium. Use slow release fertilizer with equal amounts of slow release nitrogen and potassium - 16-0-16 for instance. Avoid nitrate-nitrogen products and quick-release urea products (e.g., uncoated urea). Extra potassium may be useful in late summer and early fall. When the disease is active, frequent foliar (leaf) feeding of all nutrients (N, P, K, and micronutrients) in small amounts is necessary if the root system is severely damaged; the roots do not function properly and are unable to obtain nutrients efficiently from the soil. As the fungus does well at high pH, do not apply lime to infected turf.

Azoxystrobin (Hertiage), myclobutanil (Immunox), propiconazole (Banner Max), pyraclostrobin (Insignia), thiophanate methyl (Clearys 3336), and triadimefon (Bayleton) can be used as preventative treatments. There are a few combination products available including Armarda (trifloxystrobin and tridimefon) and Pillar G (pyraclostrobin and triticonizole) which are more effective than single products. Keep in mind that these fungicides are not as effective as the use of cultural controls once the disease symptoms are observed. These fungicides are best used preventively, meaning they must be applied prior to symptom development. Start applying the fungicides at least one month prior to the time when aboveground symptoms are normally observed. Continue applying once a month until the weather is no longer conducive to disease development. These fungicides should be lightly watered into the root zone immediately after application.