Atkinson et al. (1949) stated that late blight on tomatoes caused by Phytophthora infestans is widespread throughout the country, attacking both introduced as well as indigenous species of Solanum. In the Auckland Province it often causes crop losses of up to 50%; it damages leaves, stems, and fruit. Similarly late blight in potato crops in the Auckland area causes considerable damage. Driver (1957) showed that in Otahuhu, Auckland, five races of Phytophthora infestans were present; the disease was present throughout the year. At Lincoln, Canterbury, where late blight is present only in wet autumn seasons, only three races were present. Race 0 was collected only from diseased indigenous species of Solanum. The potato varieties 'Rua' and 'Tahi', bred by Crop Research Division, Christchurch, were resistant to all races of late blight present in New Zealand (Driver, 1960). In spray trials with potatoes at Pukekohe, Auckland, Harrow (1961) showed that maneb produced a higher yield of tubers than when copper sprays were applied to give control of late blight; both sprays gave good control of late blight.