Crop diversity are all susceptible to a single fungus, "Fusarium oxysporum" (Panama disease); large areas of the crop were destroyed by the fungus in the 1950s. 'Gros Michel' has been replaced by the current main banana on the market, the 'Cavendish', which in turn is (2015) at risk of total loss to a strain of the same fungus, 'Tropical Race 4'. Such threats can be countered by strategies such as planting multi-line cultivars and cultivar mixes, in the hope that some of the cultivars will be resistant to any individual outbreak of disease. The implications of crop diversity are at both local
Crop coefficient Crop coefficient Crop coefficients are properties of plants used in predicting evapotranspiration (ET). The most basic crop coefficient, "K", is simply the ratio of ET observed for the crop studied over that observed for the well calibrated reference crop under the same conditions. formula_1 Potential evapotranspiration (PET), is the evaporation and transpiration that potentially could occur if a field of the crop had an ideal unlimited water supply. RET is the reference ET often denoted as ET. Even in agricultural crops, where ideal conditions are approximated as much as is practical, plants are not always growing (and therefore transpiring) at