Susceptibility to Apple Scab, Nectria Cancer and Powdery Mildew of Different Unsprayed Apple Varieties

摘要

Twentyfive apple varieties were evaluated for Apple scab (Venturia inaqualis), Nectria canker (Nectria galligena) and Powdery mildew (Podosphaera leucotricha) for 4 to 7 years. The trees were grown unsprayed. The weather conditions at the experimentalorchard normally results in high infections of apple scab and low infections of powdery mildew. Infections of Apple scab is often seen also in scab resistant varieties. Williams Pride, Katinka and Katrina (scabresistant varieties) were the only varieties not showing scab in the experimental period. The two scabresistant varieties Angoldand Produkta (varieties having a poor fruit quality) was unsusceptible to Nectria canker. The reference variety Elstar/Elshofwas in all plantings among the most resistant varieties. Powdery mildew is not a problem at the experimental orchard. Most varieties had low susceptibility to Powdery mildew. Varieties with low susceptibility to diseases in general were Angola, Produkta, Rajka, Rubinola, Ahrista, Gerlinde, Gut Richard, Sukkertop, Katinka, Katrina, Marian and Primicia.