Formation and germination of Phytophthora infestans oospores in different regions of Russia.Commun Agric Appl Biol Sci. 2008; 73(2):109-18.CA
On occurrence of oospores (sexual stage), 88 Phytophthora infestans populations were investigated. The populations were collected in 14 regions of Russia. In total, 3677 samples have been checked: 2888--from potato leaflets (55 populations), 344--from tomato leaflets (16 populations), 445--from tomato fruits (17 populations). The oospores have been detected both in potato and tomato leaflets and in fruits with different occurrence--4.4%, 11.9%, and 28.8%. Occurrence of oospores per sample was also maximal in tomato fruits. After overwintering a majority of oospores (50-90%) kept their viability. Sometimes, loss of viability of some oospores was caused by the external negative influence. About 25% of oospores formed at crossing between current Russian P. infestans strains were capable to germinate. Treatment with negative temperature (-12 degrees C) or Trichoderma suspension increased percentage of germinated oospores. In some field trials, the oospores caused affection of quite many of potato plants. However, in other trials only particular plants or no plants were affected. Tomato germlings were affected only under unfavourable conditions.