December 1, 2004
- usda national organic standards,
- organic media
The USDA National Organic Standards require growers to use organically grown transplants for growing strawberries as an annual crop. However, organically grown strawberry plug transplants are not presently available in the U.S. or Canada. A study was conducted during fall 2002-03 wherein three types of plug mixes and fertilizers were evaluated for organic plug transplant production. Runner tips of 'Camarosa' strawberry were obtained from a nursery in North Carolina and planted in propagation trays. Our research demonstrated that good quality organic plug transplants can be produced under low-cost polyhouses by using organic plug mixes and organic fertilizers. Plants grown in a plug mix containing frac14; in screened pinebark and worm castings (1:1 v/v) needed to be irrigated more frequently as compared to those grown in plug mixes that contained untreated peat moss, coarse perlite, and medium vermiculite (2:1:1 v/v). Both Fertrell Super-N (4-2-4) and Fish-O-Mega (4-2-2) produced healthy transplants when used alone, but caused 'leaf burn' when used together. Therefore, when used in combination, the concentrations of Fertrell Super-N and Fish-O-Mega may need to be reduced in order to avoid leaf burn. The cultivar used in this study ('Camarosa') is highly susceptible to anthracnose fruit rot disease which was a severe problem during the unusually wet and cold fall of 2002-03. Regardless of the type of plug mix or fertilizer used, the non-marketable yields were greater than the marketable yields since many fruits that would have otherwise been marketable were rendered unfit for the market due to the severe outbreak of anthracnose fruit rot disease. Therefore, selecting cultivars that are resistant to anthracnose fruit rot will be necessary for organic strawberry cultivation in Florida. Disinfection of the runner tips prior to plug production by dipping in dilute solutions of Oxidate® or Chlorox® bleach may help reduce the incidence of this disease, and may ultimately result in improved yields.