Vegetable Disease Recognition and Management - Florida Greenhouse Vegetable Production Handbook
The major emphasis of a plant disease control program for greenhouse vegetable production is on prevention. It is far more expedient to prevent the introduction of a plant pathogen than it is to control it once it is present. The major reason for this is that few fungicides have been or are likely to be labeled for use on vegetables in the greenhouse. Four main factors discourage fungicide manufacturers from pursuing vegetable labels: 1) greenhouse vegetable acreage is insignificant when compared to field production of the same vegetables (nationwide), hence there is no profit incentive for the manufacturers, 2) worker exposure and subsequent manufacturer liability is much higher for fungicides cleared for use indoors compared to the field, 3) pesticide formulations are more apt to be phytotoxic within the protected environment of the greenhouse than in the field, and 4) pesticide residues are apt to be higher in greenhouse vegetables than in field produce due to the absence of the eroding forces of the environment (e.g., UV light, rain, etc.). With many manufacturers hesitant to expend the registration cost for product use in such high liability and low profit sites, it is imperative for growers to prevent disease problems from occurring.