Aggressivity of Different Fusarium Species Causing Fruit Rot in Melons in Brazil.

Brazil is one of the largest melon (Cucumis melo) producers in the world and most of the production is exported to international markets. Currently, over 15% of Brazilian melon shipments are lost during export transportation due to Fusarium fruit rot, which is jeopardizing the livelihood of Brazilian melon producers. We focused on understanding the aggressivity of five species of Fusarium causing fruit rot on the main types of melon produced in Brazil. We also investigated the correlation between pathogenicity and fruit quality. Experiments were performed under a completely randomized experimental design, in a 5 × 8 factorial scheme, using two methods for inoculation: deposition of discs of culture media containing fungal structures and deposition of spore suspensions in needle-punctured lesions. The fungal species used were Fusarium falciforme, F. sulawesiense, F. pernambucanum, F. kalimantanense, and Fusarium sp. Fruits of two hybrids from four types of melons, canary (Goldex and Gold Mine), piel de sapo (Grand Prix and Flecha Verde), galia (McLaren and DRG3228), and cantaloupe (SV1044MF and Bonsai), were used. Disease severity was assessed by measuring the lesions, disease severity index, fruit firmness, and degrees Brix of fruits. The five Fusarium species caused rot in the fruits of all melon hybrids studied and the aggressivity of those fungal species varied with the type and hybrid. Fruits of the hybrids McLaren and Bonsai presented the largest lesions among all melon hybrids, and hybrids of canary type (Gold Mine and Goldex) were the most tolerant to rot caused by the Fusarium species investigated. Furthermore, the greater the severity of Fusarium fruit rot, the lower the pulp firmness of the fruits, but degrees Brix did not correlate with the onset of the disease.

Agronomic characteristics and optimized sweet potato root production in monoculture under green manuring

One of the challenges of the scientific research on sweet potatoes in semi-arid environments is to increase biomass amounts of spontaneous species from the Caatinga biome, such as hairy woodrose (Merremia aegyptia L.) and roostertree (Calotropis procera Ait.), for use as green fertilizers during cultivation. Therefore, this study aimed to agronomically and economically optimize the agronomic characteristics of sweet potato root production in a monoculture, fertilized with equal amounts of biomass mixture of these spontaneous species, over two years of cultivation. The experimental design was complete randomized blocks with five treatments and five replications. The treatments consisted of equal amounts of hairy woodrose and roostertree biomass at 16, 29, 42, 55, and 68 t ha-1 on a dry basis. An additional sweet potato treatment was planted in each experiment, one without fertilizers (control) and another with mineral fertilizer, to compare with the treatment of maximum physical or economic efficiency. Sweet potato fertilization obtained the maximum optimized productive efficiency by incorporating 46.97 t ha-1 of dry biomass of M. aegyptia and C. procera into the soil. The maximum optimized agroeconomic efficiency (based on net income) of sweet potato cultivation occurred by adding 41.55 t ha-1 of dry biomass of M. aegyptia and C. procera to the soil. Using biomass from the green fertilizers M. aegyptia and C. procera is a viable technology for producers who practice sweet potato monocropping in semi-arid environments.