Anthracnose

A turfgrass disease with two forms: Either Foliar blight, or the more common, Basal rot. It is a relatively common turfgrass disease, especially of annual meadow grass; but also, of creeping bent or perennial ryegrass which can both be affected by foliar blight. However, in these other species it mostly causes a thinning of the sward, with darker lower leaves and yellowy light brown upper leaves and is usually of only minor consideration. Turf is particularly susceptible in conditions that are compacted, nutrient poor, dry (especially during drought situations), and stressed from regular close mowing, with the disease. The scientific name of this disease is Colletotrichum cereale, (formerly C. graminicola).

To identify the disease, the grass turns a sickly yellow and orangey brown colour, with the basal rotting away and small affected areas can readily merge into larger patches. The youngest leaf has also been reported as sometimes turning a reddish colour. Minute black structures, called acervuli, can often be seen at the base of the grass. Anthracnose can be seen throughout the year, but it is more prominent when the grass is growing slowly. Of the two types: Anthracnose foliar blight, affects the outer leaf tips and gradually works inwards. If left untreated this can advance to basal rot. Anthracnose basal rot destroys the base of the grass making it easy to pull out of the sward. The foliage is affected after the basal rot has commenced. This is much more serious than foliar blight.

Other factors which can contribute to this disease also include:
1. Increased plant stress due to more usage and intensive maintenance, especially scarification and verticutting.
2. Humid weather, when it is warm and cool.
3. Higher temperatures, especially greater than 22°C, especially during June, July and August, but May and September can also have high temperatures. The disease can also persist into late autumn and early winter if moist and mild weather conditions prevail.
4. Thatchy, moisture retentive turf.
5. Irrigation practices resulting in early morning surface moisture / dew.
6. Poorly drained rootzone.
7. Low soil nutritional status.
8. Low mowing heights, causing undue plant stress.
9. Poorly set mowers and blunt blades.

A wide range of practices can be carried out to help control and reduce this disease, including:
1. Keep the soil well aerated.
2. Move golf pin positions more regularly.
3. Spread wear for entry and exit points on golf and bowling greens.
4. Improve the drainage system.
5. Reduce thatch layers - both depth and density of them.
6. Box off and remove clippings.
7. Improve air circulation around the area: Consider thinning hedges or trees, removing overhanging branches.
8. Reduce annual meadow grass content.
9. Provide a more acidic soil to discourage annual meadow grass.
10. Use sulphate of iron on a regular basis to promote surface acidity.
11. Set the mower correctly and ensure the blades are sharp.
12. Raise the mowing height to reduce plant stress.
13. Apply a nitrogen fertiliser, although not much later than August on golf and bowling greens, otherwise this may encourage the more destructive Fusarium Patch disease.
14. Ensure soil potassium levels are appropriate, especially if the turf appears stressed during the summer period.
15. Manage usage. If soil conditions are unsuitable, then postpone play.
16. Chemical control.