Agrest – nowym gospodarzem dla Phytophthora cactorum

Collar rot of gooseberry, caused by Phytophthora cactorum (Leb. & Cohn) Schroet., was first time recorded in Poland in 2008 on Pax cultivar. Pax is relatively new English cultivar, which has virtually spineless bushes, high yielding and some resistance to powdery mildew. In spring, on one year old gooseberries, grown on own roots, wilting and dying of some bushes was observed. Such symptoms were not observed on gooseberry plants of Pax cv. grafted on Ribes aureum rootstock planted on the same plantation. The affected plants showed brown, water-soaked lesions appear mostly at the base of stem, typical for collar rot. Pathogen isolated from symptomatic plants was identified as P. cactorum. On LBA (Difco) medium it produces culture, homothallic mycelium with dominantly paragynous antheridia and markedly papillate, caducous sporangia, typical for this species. Resistant Ribes aureum rootstock seems to be a good solution because it keeps susceptible tissue away from infected soil. Good results in disease control were obtained after use of metalaxyl and fosetyl-Al twice during the season. These products drastically reduce new infections of gooseberries.