Ganoderma philippii (Bres. and P. Henn) Bres.

Distribution

The distribution of red root disease is worldwide. It is especially serious in China and was reported as being the second most significant root disease in Malaysia and Indonesia in an earlier IRRDB Survey. The 1998 Survey results.

Symptoms

The general appearance of the foliage of a tree infected by red root disease is similar to that of white root disease. Normally, the surface of roots infected by red root disease is coarse, as it is covered with a strongly attached layer of sandy soil particles. This layer of soil is absent on roots infected by white root disease and is often used to differentiate the two diseases. After washing, a layer of reddish-coloured mycelia is visible on the surface of the roots.

The fruiting bodies are large with dark-brown corrugated upper surfaces, whitish lower surfaces and creamy white edges.

Disease spread

As with white root disease, the principal means of spread is by root contact with remnants of diseased roots following land clearing, and the subsequent spread is by tree-to-tree root contact. The rate of advance of the mycelia, which do not extend much further than the rot, is slower than the rate of advance of rhizomorphs of R. lignosus. Hence, the destruction caused by red root disease is normally more serious on trees that are over eight years old.

Disease control

Cultural practices

Proper land clearing and planting of creeping legume covers as prescribed to reduce the incidence of white root disease are also beneficial in reducing the incidence of red root disease. Mechanical clearing is especially effective compared to with other clearing methods.

Chemical treatment

There is no evidence that sulphur soil amendment helps to reduce the incidence of red root disease. Similarly, no fungicide has yet been recommended for application by soil drenching for the treatment of the disease. In Malaysia and several other countries, the disease is treated by applying collar protectant dressing containing tridemorph.