Routine application of artificial frost treatment needs a detailed, exact technology, which would ensure the reliability of the results obtained. Buds being on spurs loose their frost resistance sooner because of their quick development. According to these results to examine samples containing both types of buds can lead to significant mistakes. Considering our experiences it seems that a sample containing 200 buds provides the reliable correctness. Further increasing of sample size decreases the value of deviation but it is not proportional to the work needed for the experiment. The following treatments are suggested: deep dormancy phase: -24 --26°C, directly after deep dormancy:-21 --24°C.

The appearance of resistance to powdery mildew was investigated on seedling progenies of interspecific crossings. Hybrids of American and East-Asian wild species and one Vitis vinifera variety (Janjal kara) were used as source of resistance in the crossings. The resistance of foliage and of berries were tested in the field at the time of vintage. The degree of resistance was ranked into six classes. In American and Asian hybrid derivatives there were few highly resistant progenies, but in the hybrids of Janjal kara variety more than 90 % of the progenies proved to be highly resistant to powdery mildew. According to the distribution of classes of resistance in the populations the resistance of American and Asian sources are mostly influenced by additive gene affects. The resistance of Janjal kara seemed to be mono or digenic. No close correlation was found between the powdery mildew resistance of the foliage and that of the berries.

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