Abstract

Downy mildew of common sage (Salvia officinalis), caused by Peronospora salviae-officinalis, has become a serious problem in sage production worldwide. The effect of temperature was determined for conidia germination and disease development. In vitro, conidial germination rate was highest at temperatures between 10 °C and 20 °C and was strongly reduced at temperatures above 25, but conidia were also able to germinate at 2 °C. Temperatures between 15 and 20 °C were most favourable for infection and disease progress in infection experiments in climate chambers, with highest sporulating leaf area observed at 15 and 20 °C, and highest symptomatic leaf area at 20 °C. P. salviae-officinalis is still able to infect sage plants at 5 °C, but sporulation was only observed at higher temperatures. Oospores developed 14 days after inoculation at 15 °C, and 8 days after inoculation at 20 and 25 °C. The infection trials also showed that dark incubation is not a prerequisite for successful infection of sage. Furthermore, P. salviae-officinalis needs two events of leaf wetness or high humidity to complete its asexual life cycle. First, a leaf wetness event of at least three hours is needed for conidial germination and penetration of the host. Second, high humidity of at least 90% is needed at the end of the infection cycle for sporulation. Seed washing revealed the presence of P. salviae-officinalis oospores in seed lots of sage suggesting that infested seeds might play a major role in the fast spread of sage downy mildew, which is an important finding for phytosanitary or quarantine measures.

中文翻译：

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鼠尾草霜霉病的流行病学（Peronospora salviae-officinalis）

摘要

由鼠尾草（Peronospora salviae- officinalis）引起的普通鼠尾草（Salvia officinalis）的霜霉病已成为全世界鼠尾草生产中的严重问题。确定温度对分生孢子萌发和疾病发展的影响。在体外，分生孢子的发芽率在10°C和20°C之间时最高，而在25°C以上的温度下则大大降低，但分生孢子也能够在2°C时发芽。在气候箱的感染实验中，温度在15至20°C之间最有利于感染和疾病进展，在15至20°C时观察到的孢子叶面积最高，而在20°C时则出现症状的叶面积最高。丹参假单胞菌仍然能够在5°C感染鼠尾草，但只有在较高温度下才能观察到孢子形成。卵菌在15°C接种14天后以及20和25°C接种8天后发育。感染试验还表明，暗培养并不是成功感染鼠尾草的前提。此外，丹参假单胞菌需要两次叶湿或高湿事件来完成其无性生活周期。首先，分生孢子萌发和穿透宿主需要至少三个小时的叶子湿润事件。其次，在感染周期结束时，至少需要90％的高湿度才能形成孢子。种子清洗后发现丹参假单胞菌的存在 鼠尾草种子中的卵孢子表明，被侵染的种子可能在鼠尾草霜霉病的快速传播中起主要作用，这是植物检疫或检疫措施的重要发现。