Neonectria fruit rot (NFR), an apple disease caused by the fungus Neonectria ditissima, is common in Brazilian orchards, but several aspects of its epidemiology are not well elucidated. The objectives of this study were to: i) test in vitro germination of ascospores at different temperatures and wetness periods and compare with conidia germination, ii) evaluate and compare the monocyclic components of NFR caused by conidia and ascospore infection in wounded and unwounded ripe detached ‘Gala’ apple and iii) evaluate and compare the monocyclic components of NFR caused by conidia infection in ‘Rocha’ pear fruit under different temperatures. Germination of conidia and ascospores occurred in the range of 12–28 °C. At 35 °C no germination occurred, for both ascospores and conidia, regardless of the wetness period (3–60 h). With the same wetness period, conidia germination was always higher than ascospores at any temperature. For ascospores, the optimal temperature for germination ranged from 18–21 °C, lower than the estimated for conidia, which ranged from 21 to 24 °C. In wounded detached apple fruit, the incubation period varied from 35 to 49 days after ascospore inoculation, and for conidia from 14 to 42 days. When comparing the same temperatures, mean lesion growth rate was always higher for fruits inoculated with conidia than with ascospores. Unwounded fruits inoculated in the calyx-end did not present Neonectria fruit rot symptoms. The disease on ‘Rocha’ pear fruit has shorter incubation and latent periods than those of ‘Gala’ apple and higher AUDPC at 25 °C. The fast monocycle development represents a risk if the disease spread to pear orchards but also sets pear fruit as a good option for future NFR control studies.

Neonectria 果腐病 (NFR) 是一种由Neonectria ditissima真菌引起的苹果病，在巴西果园中很常见，但其流行病学的几个方面尚未得到很好的阐明。本研究的目的是：i）在不同温度和湿度下测试子囊孢子的体外萌发并与分生孢子萌发进行比较，ii）评估和比较受伤和未受伤的成熟分离体中分生孢子和子囊孢子感染引起的 NFR 的单环成分‘Gala’苹果和iii)评估和比较不同温度下‘Rocha’梨果实中分生孢子感染引起的NFR的单环成分。分生孢子和子囊孢子的萌发发生在12-28℃范围内。在 35°C 下，无论湿润期（3-60 小时）如何，子囊孢子和分生孢子都不会发芽。相同湿度条件下，任何温度下分生孢子萌发率均高于子囊孢子。对于子囊孢子，发芽的最佳温度为 18-21 °C，低于分生孢子的估计发芽温度（21-24 °C）。在受伤的分离苹果果实中，子囊孢子接种后的潜伏期为 35 至 49 天，分生孢子的潜伏期为 14 至 42 天。当比较相同的温度时，接种分生孢子的果实的平均病斑生长率总是高于接种子囊孢子的果实。在花萼末端接种的未受伤的果实没有表现出新果属果实腐烂的症状。 'Rocha'梨果实上的疾病比'Gala'苹果的潜伏期和潜伏期更短，并且在25℃下AUDPC更高。如果疾病传播到梨园，快速的单循环发展会带来风险，但也使梨果实成为未来 NFR 控制研究的一个不错的选择。