Take-all is caused by the fungus Gaeumannomyces graminis which is a root-rot pathogen of cereals and grasses. The fungus survives by overwintering in dead plant debris and residue. This soil-borne pathogen infects living roots, progressing into the stele of the root, slowly killing the plant. After a number of roots go through this process, the plant dies. Once the host dies, the fungus completely takes over the dying plant tissue, finishing its cycle. Transmission through water, wind, animals, and/or equipment is all common.
Take-all Identification and Habitat
Initially, infected crops will show some lack of growth and they will appear in patches. Diseased plants will be discolored in their roots, crown, and stem base. More specifically, roots tend to be blackened in the center and may have small lesions in early infections of take-all. White-heads can appear further on in the season, which is a good sign of disease. In grasses, take-all will often result in circular dead patches in the field.
- • G. graminis var. tritici – pathogen of wheat and barley crops
- • G. graminis var. avenae – pathogen of oats
- • G.graminis var. graminis – affects maize and rhizomatous
The main predictor of take-all is fields sandy soils with poor soil drainage. Wet soil is very good for take-all growth. In dry conditions, the symptoms of take-all are generally much less noticeable. Soil with imbalanced levels of nitrogen, phosphorus, and other elements may be more susceptible to disease development. Furthermore, soil pH plays a role in disease development. Soil at a pH of 7.0 tends to cause worse damage to crops. In terms of temperature, warm to hot temperatures are most favorable.
Take-all Management and Control Methods
First, tillage is a good method of removing any remaining infected plant residue from the surface of the soil. This process helps break down the fungus that infects crops, making it a crucial part of dealing with take-away. As take-all can survive on grassy weeds, controlling weed populations surrounding crops is a good idea when trying to reduce chances of infection and spread of disease. Because wet soil is conducive to the disease, improving/maintaining proper soil drainage is very important. Furthermore, keeping soil pH below 6.0 will help limit disease development. Irrigation should be somewhat infrequent and as deep as possible to avoid overly wet soils. Before working with crops, allow soil to dry to avoid spreading the pathogen from an infected plant to other non-infected plants. Lastly, resistant cultivars can be very useful in avoiding the disease entirely. Always consider using resistant crop breeds.
Foliar fungicides are not effective in treating this disease, but applying sterol-inhibiting and strobilurin fungicides can help terminate take-all symptoms in bentgrass turf. Before using fungicides, be sure to read the label carefully for cautionary advice and application guidelines.