The diseases and pests of the rubber tree . ing to control the fruit disease by cutting ofidead branches and removing the green fruits. If the fruitsare removed the chief source of Black Thread infection isabolished. During an attack of fruit disease the fungusproduces spores in abundance on the diseased fruits, andthese, washed down, or splashed on to the tapping cut, setup Black Thread. From South India it is reported thaton one-estate on which dead branches and green fruits IV PHYTOPHTHORA DISEASES 123 had been removed over an area of 100 acres as an experiment,Black Thread was much less pr
The diseases and pests of the rubber tree . ing to control the fruit disease by cutting ofidead branches and removing the green fruits. If the fruitsare removed the chief source of Black Thread infection isabolished. During an attack of fruit disease the fungusproduces spores in abundance on the diseased fruits, andthese, washed down, or splashed on to the tapping cut, setup Black Thread. From South India it is reported thaton one-estate on which dead branches and green fruits IV PHYTOPHTHORA DISEASES 123 had been removed over an area of 100 acres as an experiment,Black Thread was much less prevalent on the experimentalarea than on any other part of the estate, the differencebeing very great. Black Thread disease has not been known to kill a the raias cease the decay stops. In the case ofslight attacks the result is a series of narrow vertical wounds,each surrounded by a swollen callus, and though thesewounds soon heal over, vertical swollen ridges are left whichmake the renewed tapping surface uneven. In bad attacks,. Fig. 14.—Black Thread ; an old wound, x J. where the vertical wounds have coalesced laterally, a largeopen wound extends right across the tapping cut, and thismay not heal over for several years. In any case therenewed bark is uneven and irregular, and may not be in afit condition for retapping at the appoiated time. Black Thread may be combated either by a preventiveor a curative treatment. Of the two there appears to belittle doubt that preventive treatment will ultimately begenerally adopted in countries where this disease is consists of painting over the tapping cut with a pre-servative, or fungicide, after every tapping during the 124 THE RUBBER TREE hap. rainy season. Weak solutions are employed, it having beenfound that 5 per cent is usually a sufficient strength. Bruno-linum, Brunolinum Plantarium, Carbolineum Plantarium,Solignum, Agrisol, and Jodelite have all been found addition to the above, Jeyes Flu
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