CALCIUM APPLICATIONS BEFORE HARVEST AFFECT THE SEVERITY OF ANTHRACNOSE FRUIT ROT OF GREENHOUSE-GROWN STRAWBERRIES

B.J. Smith, C.L. Gupton
Anthracnose fruit rot of strawberry caused by Colletotrichum acutatum may result in severe crop losses during a wet harvest season. Fungicides currently registered for use on strawberry in the United States do not control this disease. The effect of calcium solutions applied to greenhouse grown strawberry plants before harvest on anthracnose infection of ripe fruit was evaluated in two studies. In study I, two application methods (soil drench and foliar spray) of three calcium sources (calcium sulfate, calcium chloride and calcium nitrate at 2.5 mM Ca++ prepared in ¼ strength Hoagland's solution) were compared. In Study II, soil-drench applications of five concentrations (0, 1.25, 2.5, 5 and 10 mM Ca++) of each of the three Ca sources were compared. Treatment solutions were applied 3 times weekly beginning 6 weeks before harvest and continuing through harvest (13 wks total). Ripe fruit from treated plants were harvested, and inoculated with a conidial suspension of C. acutatum.

Fruit rot development was rated 72 hr and 96 hr after inoculation. In Study I fruit from plants receiving drench or foliar applications of calcium sulfate developed less fruit rot than fruit from plants receiving water or the calcium chloride or calcium nitrate treatments. Fruit from plants receiving foliar applications of CaCl2 developed less fruit rot than that from plants receiving soil applications of calcium chloride. In Study II, calcium sulfate at 2.5 mM and ¼X Hoagland's solution resulted in the lowest fruit rot severity ratings.

Smith, B.J. and Gupton, C.L. (1993). CALCIUM APPLICATIONS BEFORE HARVEST AFFECT THE SEVERITY OF ANTHRACNOSE FRUIT ROT OF GREENHOUSE-GROWN STRAWBERRIES. Acta Hortic. 348, 477-482
DOI: 10.17660/ActaHortic.1993.348.97
https://doi.org/10.17660/ActaHortic.1993.348.97

Acta Horticulturae