S U M M A R YWith 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.

SUMMARY Several fungicides chosen for their ability to control the pathogens previously isolated from stored corms of taro failed to prevent severe rotting. This result led to a reappraisal of the organisms involved in the initial stages of decay. Isolations made from stored corms during the first 5 days showed that Phytophthora colocasiae and Pythium splendens were the dominant fungi in the rots. Later Botryodiplodia theobromae rapidly colonized the corms to complete the decay. Attempts to reduce losses by leaving petiole bases, cormels and roots attached only succeeded in delaying infection by a few days. Corms placed in soil in well‐drained pits stored relatively well up to 4 wk without impaired taste. Fungal rots were completely eliminated in corms stored in the soil but bacterial rots caused by Erwinia chrysanthemi were responsible for some decay.

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S U M M A R YTwo virus diseases, alomae and bobone, both of which are spread by the planthopper Tarophagus proserpina affect taro (Colocasia esculenta) on Malaita, Solomon Islands. Where the diseases were endemic, plants of 284 of 297 cultivars died from alomae infection; the remaining 13 showed bobone symptoms on three to five leaves and then recovered, but symptoms later recurred on 12-13% of plants. Loss of yield due to alomae infection was directly proportional to the percentage of plants infected. Losses due to bobone of c. 25% could not be reliably detected unless insect pests were controlled. Frequent sprays with 0.1% malathion had no appreciable effect on the incidence of alomae, but fewer plants (30%) were infected when planted in November or December than when planted in May, June or AugustBecause new taro crops are traditionally grown close to infected crops, insecticidal control of the vectors will probably be of limited use in decreasing spread of the diseases.(64-94%).

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