THE COTTONBALL DISEASE OF CRANBERRY IN WISCONSIN: POTENTIAL FOR DISEASE MANAGEMENT WITH FUNGICIDES

Cottonball, caused by Monilinia oxycocci, is the most important disease problem affecting cranberries in Wisconsin.
Currently only the fungicide triforine is registered for cottonball management, and it has not been consistently effective.
In 1987, triforine, cupric hydroxide, myclobutanil, benomyl, thiophanate-methyl, vinclozolin, iprodione, and two experimental fungicides from Rohm and Haas Company (RH-7592 and RH-3486)—all reported to be effective against other species of Monilinia—were evaluated for disease management in a commercial field with a recurring cottonball infestation.
All fungicides were applied on 30 April (bud break) and 12, 20, and 29 May to control primary infection of shoots by ascospores and on 16 (50% bloom) and 24 June to control secondary infection of flowers by conidia.
Fungicides were differentially effective at controlling primary and secondary infections.
All treatments except iprodione and thiophanate-methyl significantly reduced the number of infected shoots.
Triforine and RH-7592 were most effective; RH-3486 and vinclozolin provided protection that was significantly better than the remaining fungicides tested.
Benomyl and triforine were most effective at limiting secondary infections of flowers.
In addition, thiophanate-methyl, vinclozolin, RH-7592, RH-3486, and iprodione provided some protection, but cupric hydroxide and myclobutanil provided none.
Consequently, the potential for managing the cottonball disease with fungicides appears promising.

IV International Symposium on Vaccinium Culture

S.N. Jeffers

https://doi.org/10.17660/ActaHortic.1989.241.54