Studies on the taro leaf blight fungus Phytophthora colocasiae in Solomon Islands: control by fungicides and spacing

Autor: D. E. Gollifer, G. V. H. Jackson, F. J. Newhook
Rok vydání: 1980
Předmět:
Zdroj: Annals of Applied Biology. 96:1-10
ISSN: 1744-7348
0003-4746
Popis: SUMMARY With mist blower application, copper oxychloride at 2.25 kg/ha was effective in controlling PHYTOPHTHORA colocasiae but mancozeb at 3.6 kg/ha was not. Phytotoxicity from captafol at 1.8 and 3.6 kg/ha nullified any potential gain in yield from control of blight. Leaf removal from healthy plants to maintain four leaves per plant for 90 days, to simulate roguing of leaves for disease control, was shown to cause no loss in yield. However, regular roguing of diseased leaves over the same period in plots affected by a severe epiphytotic did not eradicate the pathogen. When roguing ceased at 90 days disease increased rapidly to epidemic proportions that seriously affected final corm yield. An attempt to reduce the effect of blight by wider than traditional spacing was unsuccessful. Under continuous epiphytotic conditions disease had the maximum possible impact regardless of spacing. Whereas plants free from competition normally bear six to seven leaves, this number was reduced by severe disease to three or four, the same number as was borne by plants under the competitive conditions of closer-than-traditional spacing. Instead of the traditional 20–30 000 plantdha, it was shown that density can be doubled under conditions of high leaf blight hazard and increased yields still be obtained.
Databáze: OpenAIRE
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