關於馬鈴薯晚疫病的預測和防治的研究(摘要)

三年的觀察顯示馬鈴薯地裡出現的中心病株是當年該病開始流行的標誌。在華北北部的條件下,到開花期才可能發現最早的中心病株。田間只有個別的植株成爲中心病株。即便完全播種病薯也是如此。通常在植株特別茂密、開花較早的低窪地點最容易發現中心病株。在田間的一般植株還沒有任何感染的跡象時,中心病株就已經有了眾多的典型病斑,並且其下層葉片開始發黃。隨後,病害從中心病株順着風向往周圍的植株擴展。但是,傳播的距離是有限的。在觀察的一個典型實例中,中心病株發現後經過10天,田間全部病斑數目的檢查表示90%以上的病斑分佈於中心病株周圍大約800平方米的面積上(圍1)。在晚疫病可能流行的季節中,每次侵染的潛育期相當恒定,變動的幅度僅在3至4

STUDIES ON THE FORCASTINC AND CONTROL OF POTATO LATE BLIGHT

Appearance of sporadic diseased-plant centers has repeatedly been shown to be a good signal for forcasting the current year's outbreak of potato late blight in an individual farm. Under North China conditions, diseased-plant centers have never been found before the blooming period. Only a very few plants within a large area of potato plantation act as disease-spreaders, even if all plants are grown from infected seed-tubers. They are usually located at places with poor drainage and dense stand. Before all o...