棚栽嫁接西瓜黄瓜绿斑驳花叶病毒病发病动态及其田间扩展研究初报

为明确棚栽嫁接西瓜黄瓜绿斑驳花叶病毒病发生规律，对该病害的发病、蔓延和影响因素进行研究。毛竹搭建塑料大棚，无毒土壤上常规或低密度移栽健康嫁接西瓜苗，移栽后6、30天剪除部分瓜苗顶叶或倒2叶约半片后，将伤口浸渍在毒源中进行接种诱发，常规密度移栽苗自然生长，低密度移栽苗经整枝始终保持单株独立；健康植株用毒源污染剪刀、手指后整枝或毒源与健康藤蔓摩擦诱发。调查病田病株自然扩展以及拔除清除病健株后直播种子和套种瓜苗的控病效果。目测法定期调查显症病株，酶联免疫双抗体夹心检测法确定病株。接种后植株染病率高。低密度移栽苗：移栽后6天接种的瓜苗24天显症、34天突增、85天高峰，分别比移栽后30天接种的植株长4、4和30天；未接种的也在移栽后70天显症、95天高峰。常规密度移栽苗接种株也有类似趋势。显症病株率和带毒株率与日平均温度关系密切。病株中不同藤蔓上的叶片和相同藤蔓内的叶片既表现显症，也有隐症，甚至终生带毒隐症。病健藤蔓摩擦病株率100.0%，而染毒手指、剪刀整枝病株率则为91.7%和83.3%。病田内病情自然扩展先相邻连续，后点片；病地拔除清除病健株后，直播瓜苗和套种嫁接苗带毒株率分别为82.4%和77.0%，控病效果17.6%和23.0%。棚栽嫁接西瓜苗（植株）从感染黄瓜绿斑驳花叶病毒病到表现症状需要20天左右的潜伏期，继之产生显症病株突增和高峰，温度高，潜伏期短、进入突增和高峰快；隐症病株表现在株间、不同分枝藤蔓叶片间和相同藤蔓不同叶片间；移栽密度对发病无明显影响。田间扩展再侵染先相邻后点片，除了其他途径外，病健藤蔓接触摩擦传病作用大；病地当年连作重发的机率高。

Outbreak Dynamics and Field-extension of Cucumber Green Mottle Mosaic Virus in Grafted Watermelon Cultured in Greenhouse

To clarify the rule of cucumber green mottle mosaic virus disease in greenhouse grafted watermelon, the cause, spread and effect factors of the disease were studied. In greenhouse built by bamboos, healthy grafted watermelon plants were transplanted in virus-free soil conventionally or in low-density form. Top leaves of the plants were cut or leaves were cut by half after 6 days and 30 days. Then the wounds were dipped in virus to induce inoculation. Conventional transplanted plants grew naturally, while those in low-density form maintained independent. Healthy plants were induced by pruning with virus-contaminated scissors or fingers, and friction between healthy and sick vines induced plants as well. Then, natural spread of sick field and sick plants was investigated, and disease control effects of seeds without sick plants and interplanting melon plants were investigated too. Sick plants with symptoms were researched by visual method regularly, and confirmed by Double Antibody Sandwich Enzyme-linked immunosorbant assay (DAS-ELISA) method. Plants’ infection rate was high after inoculation. For transplanted plants in low-density form, inoculated plants which were transplanted after 6 days showed symptoms in 24 days, increased rapidly in 34 days and reached peak in 85 days, which were 4 days, 4 days and 30 days longer than those of plants inoculated 30 days after transplanting. Plants without inoculation showed symptoms in 70 days and reached peak in 95 days after transplanting. Conventional transplanted plants with inoculation shared a similar trend. Sick rates of plants with symptoms and plants with virus were closely related to the daily average temperature. Leaves between different vines and those on the same vines of sick plants displayed both obvious symptoms and hidden symptoms, and even lifetime hidden symptoms with virus. Sick rate of plants caused by friction between healthy and sick vines reached 100%, while methods of pruning with virus-contaminated fingers and scissors led to the rate of 91.7% and 83.3%. In sick field, virus spread adjacently, and then substantially. After getting rid of sick plants in the field, sick rates of melon plants and interplanting grafted plants were 82.4% and 77.0%, while the rates of disease control effect were 17.6% and 23.0% respectively. In conclusion, it takes 20 days’ incubation for greenhouse grafted watermelon (plants) to display sick symptoms from infecting cucumber green mottle mosaic virus. Afterwards, the amount of sick plants increases rapidly and reaches the peak. It has features of high temperature, short incubation, sudden increase and reaching the peak rapidly. The symptoms of hidden sick plants show in leaves between plants and vines, and also different leaves on the same vines. The influence of density of transplanting on the disease is not obvious. The disease spreads in the field adjacently first, and then substantially. The effect of friction between healthy and sick vines on virus transmission is great besides other methods. Succession cropping in sick field of the year has high probability of recurrence.