The results showed that there was a clear disease reduction when the two spray programs (SP1 and SP2) were used as compared with the farmers’ practice and the research recommendation of only spraying three to four times with measures that have been used for years. Demonstrations were conducted during one of the high disease pressure seasons, with many farmers within the farming communities experiencing total crop failures due to LB.
The 8-week spray programs provided by the companies proved to be more effective in managing the disease even under high pressure. LB progress was significantly reduced when the disease was controlled weekly with SP1 and SP2. Disease development was quite high in uncontrolled plots - reaching 100% in some varieties within a span of two weeks (control). This shows that farmers need to control the diseases early enough to avoid massive losses. Significant reduction was also observed with the bi-weekly spray program with SP1 and SP2.
Given other constraints that the farmers are faced with, they normally cannot afford to spray weekly as required. The result shows that the other option could be to spray bi-weekly to save some of their yields from the devastating disease. The results also show the importance of using host resistance as an alternative to manage the disease as observed with the variety ‘Connect’, which was not affected by LB. Significant increases in yields under different spray regimes (SP1 and SP2) were reported.
Yield loss of more than 60% (comparison of control and weekly spraying) was reported for the local variety if not controlled for with crop protection measures. The results also show that there is a difference in how the disease impacts the yields of different varieties. The experience gained shows that there is an immediate need for capacity building (i.e. extension etc.) on IPM3 for the identification of potato diseases and pests as well as plant protection measures such as uprooting infected plants and crop rotation but also training on correct application times and rates for agro-chemicals among farmers. Safety training with regard to human health and the environment play an essential role as well. Such training can be undertaken at reasonable scale.
3 FAO definition: Integrated Pest Management (IPM) means the careful consideration of all available pest control techniques and subsequent integration of appropriate measures that discourage the development of pest populations and keep pesticides and other interventions to levels that are economically justified and reduce or minimize risks to human health and the environment. IPM emphasizes the growth of a healthy crop with the least possible disruption to agro-ecosystems and encourages natural pest control mechanisms.