Studies on the development of Globodera rosfochiensis in potato cultivars with different levels of resistance have shown that both males and females of the nematode complete their whole cycle of development in susceptible cv. Svitanok Kyivskii in 61 days. In resistant cv. Vodograi, only males complete their development. Development of females is interrupted at the third larval instar, and mature females do not appear.

Control ofGlobodera rostochiensis in Ukraine depends on the use of resistant potato cultivars. In the last 2years. the proportion of resistant entries in the official Ukrainian list has increased from 27% to 4 5 8 , and the number of Ukrainian-bred resistant cultivars has increased from 3 to 12. It is now suggested that resistant cultivars are classified into the categories 'resistant and tolerant' and 'resistant but only relatively tolerant'. The choice of these cultivars should depend on the nematode population of the soil. Control of Difylenchus destructor is also considered, on the basis of prophylactive and agrotechnical measures.

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