INFORMATION ABOUT PLEIONES

FROM THE R.H.S.

(1) Black Spot

Blackened lesions on leaves and sterns of orchids are associated with several pathogenic fungi and bacteria worldwide, but the cause often remains undetermined. In a single sample of affected Pleiones submitted to Wisley in 1999, the fungus CoI1etotrichum gloeosporioedes was associated with spreading blackened, sunken lesions on the pseudobulbs. This fungus is known to cause anthracnose (Blackened lesions) worldwide on a wide range of plants and may also be present as a secondary pathogen, only growing when tissues have been damaged by other means.

As tests were not carried out in the case submitted to Wisley, it cannot be claimed for certain that this fungus was the cause of the Pleione problem, but it is likely because Colletotrichum causes similar symptoms in other orchid genera. No fungicides are available to home gardeners for the control of

anthracnose.

Always buy healthy stock. Remove and destroy any plants showing symptoms immediately, before the fungus has time to produce its pink, water-dispersed spores which spread the disease from one plant to another.

(2) Latest Findings

The following is information about one of the new plants listed in the latest edition of the R.H.S Plant Finder (i.e. the 200012001 edition).

The bright yellow, heavily marked lip of Pleione San Salvador - a new grex from National Plant Collection Holders Butterfield Pleiones - echoes the famous Shantung grex, one of its parents. The other is file yellow-flowered species Pleione forrestii.