Poster Session: Diseases of Plants - New and Emerging Diseases
525-P
Pestalotiopsis spp., a newly discovered root pathogen of strawberry transplants.
J. MERTELY (1), M. Chamorro (2), N. A. Peres (2)
(1) Univ of Florida-GCREC, Wimauma, FL, U.S.A.; (2) University of Florida-GCREC, Wimauma, FL, U.S.A.
Florida strawberries are planted in the fall for fruit production during the winter and spring. Rapid establishment of transplants is necessary for early production when market prices are high. We have repeatedly isolated Pestalotiopsis spp. from weak and dying strawberry transplants in commercial fields and suspect it may contribute to establishment difficulties. Four strawberry root isolates were tested for pathogenicity in replicated greenhouse experiments. In Aug. 2013, the roots of cut-top transplants (cultivar Strawberry Festival) were briefly dipped in inoculum and planted in pots filled with fumigated field soil. The inoculum consisted of 10-day-old PDA cultures bended with sterile water. After 2 weeks, stunting and/or premature dying of older leaves was observed on 16 of 20 inoculated plants, and 2 of 10 control plants. Pestalotiopsis was subsequently reisolated from necrotic crowns of several plants. In Aug. 2014, the same isolates were retested using inoculum calibrated to 2 x 105 conidia/ml. After 2 weeks, plant mortality ranged from 17 to 83%, depending on the isolate, whereas none of the controls had died. Several collapsed partially green plants developed a basal crown rot from which Pestalotiopsis was reisolated. Based on spore morphology and host preference, our isolates appear to be P. longisetula, a known pathogen of strawberry fruit and leaves. However, sequencing of the ITS region suggest a close relationship to P. clavispora.