Page 93 - Ecuador's Banana Sector under Climate Change

chapter 4: assessment of climate change impact on banana production and suitability in ecuador, and general assessment of global banana trends under climate change scenarios
Since temperatures are projected to increase from current levels through 2070, this could result in increased growth rates for the germination tube of spores of BS and more rapid disease development. As shown in Figure 20, little increase is projected for 2030 over current rates but, by 2050 and 2070, the velocity of evolution is projected to increase.
A second approach to projecting the effect of average climate change is based on the state of evolution or advance of the disease. In general, leaf infection by BS ascospores is not observed in the absence of leaf wetness. Infection by BS conidia occurs at leaf wetness between 0 to 18 hours. Leaf lesions are presented 14 days after inoculation of plants subjected to 18 hours of leaf wetness (Jacome and Schuh, 1992). In general, the development of BS in the field could be monitored
by the evolution state of BS in leaf four (EE4H) or leaf five (EE5H). Weekly changes of the state of evolution can then be used to predict the need for fungicide applications. Taking into account the delay of the disease in 14 days, Pérez et al. (2000) developed a model to predict the evolution state of leaf four (EE4H), based on the accumulated rainfall for 14 days five weeks before the date of predictions and the average potential evapotranspiration two weeks before the date of prediction (Pérez et al., 2000). The following equation was used:
EE4H= 1812 + 6.24 * Rainfall145W - 198.2 * (ETo2W/0.8)
Where EE4H is the actual estate of evolution of the disease in leaf four, rainfall is the cumulative 14 days rainfall five weeks before and the ETo is the weekly average ETo two weeks before. The coefficient 0.8 was used due to the fact that the original equation used the evaporation estimated by the Piche evaporimetre which overestimated the evaporation.
Figure 20 Sums of velocity of BS evolution, based on temperature
16000
14000
12000
SR STATION SR 2070 SR 2050 SR 2030 SR CURRENT
Week
100002 7 12 17 22 27 32 37 42 47 52
Source: Authors’ elaboration, using downscaled weather data from MarkSim weather generator
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Week SR of m. fijiensis