A search for anthracnose resistant cashew cultivars in Mozambique

Dwarf and common cashew (Anacardium occidentale) genotypes were screened separately for resistance against anthracnose (Colletotrichum gloeosporioides). Disease incidence was assessed on emerging leaves over three consecutive crop seasons in Mocuba, Meconta and Pebane districts of northern Mozambique. Evaluation the disease using leaf incidence is presented as a new field method for screening cashew genotypes resistant to anthracnose. It is fast, precise and consistent in ranking cultivars over several tree seasons. Seasonal, cultivar and disease incidence means were compared using Fishers’ LSD test. The method enabled the differentiation of highly infected cultivars from those consistently tolerant across seasons and locations. No a single clone with a high level of resistance was identified out of 229 entries. However, hierarchical tables of clonal sensitivity ranked clones 1.12PA, 12.8PA and 1.18PA as tolerant and 11.9PA and 2.3BG as susceptible among the dwarfs. Among the common genotypes, clones NA7, MB77, 1.5R and MCH-2 ranked tolerant and IM1 and MU3 susceptible. Tolerant clones were therefore recommended to be used in the national cashew breeding program for further development of cashew cultivars with durable resistance to anthracnose. Further, clones such as 2.5VM, 1EM, MB75 and others that revealed incidence consistency over seasons can be used as susceptibility or tolerance standards in screening trials.AFD (French Development Agency, Mozambique) was funding this research through the PRC/PIAC-Project, Nampula.www.elsevier.com/locate/croprohb201

Epidemiology of cashew anthracnose (Colletotrichum gloeosporioides Penz.) in Mozambique

Anthracnose of cashew (Anacardium occidentale) was studies on various genotypes and locations in Mozambique. Colletotrichum gloeosporioides was identified as the anthracnose causal agent using polymerase chain reaction. The relationships between incidence and severity of anthracnose on cashew genotypes were statistically analyzed by regression. Anthracnose leaf incidence, which is practically easy to evaluate, was consistently associated with leaf severity, and their relationships can be estimated using the restricted exponential function across locations, crop seasons, genotype and fungicide trials. Pooled data enabled estimation of initial incidence of 1.43% with percentage variance accounting for 83.2 and standard error of 8.3. By computing incidence data into the summary equation, 24 changes of 0, 1, 5, 10 and 40%, resulted in changes of severity estimates of 0.01, 0.05, 0.10, 0.50 and 1.00%, respectively. The maximum disease incidence was estimated as 80% when the severity reached only 5%. Increase in severity was observed afterward, approached a maximum of 25% when leaf detachment is observed. The use of incidence data for epidemic comparisons, genotype and fungicide evaluation in cashew orchards is recommended. Anthracnose incidence on leaves however, could not predict incidence on nuts.The AFD (French Development Agency, Mozambique) funded this research through PRC/PIAC-Project.www.elsevier.com/locate/croprohb201

A search for anthracnose resistant cashew cultivars in Mozambique

Dwarf and common cashew (Anacardium occidentale) genotypes were screened separately for resistance against anthracnose (Colletotrichum gloeosporioides). Disease incidence was assessed on emerging leaves over three consecutive crop seasons in Mocuba, Meconta and Pebane districts of northern Mozambique. Evaluation the disease using leaf incidence is presented as a new field method for screening cashew genotypes resistant to anthracnose. It is fast, precise and consistent in ranking cultivars over several tree seasons. Seasonal, cultivar and disease incidence means were compared using Fishers’ LSD test. The method enabled the differentiation of highly infected cultivars from those consistently tolerant across seasons and locations. No a single clone with a high level of resistance was identified out of 229 entries. However, hierarchical tables of clonal sensitivity ranked clones 1.12PA, 12.8PA and 1.18PA as tolerant and 11.9PA and 2.3BG as susceptible among the dwarfs. Among the common genotypes, clones NA7, MB77, 1.5R and MCH-2 ranked tolerant and IM1 and MU3 susceptible. Tolerant clones were therefore recommended to be used in the national cashew breeding program for further development of cashew cultivars with durable resistance to anthracnose. Further, clones such as 2.5VM, 1EM, MB75 and others that revealed incidence consistency over seasons can be used as susceptibility or tolerance standards in screening trials.AFD (French Development Agency, Mozambique) was funding this research through the PRC/PIAC-Project, Nampula.www.elsevier.com/locate/croprohb201