Webber Janette, Bruce Chapman R, Worner S P
Bio-Protection and Ecology Division, P.O. Box 84, Lincoln University, 7647, Christchurch, New Zealand.
Exp Appl Acarol. 2008 Jun;45(1-2):39-51. doi: 10.1007/s10493-008-9163-9. Epub 2008 Jun 12.
Eriophyoid big bud mites are key pests of hazelnut throughout the world, but they are difficult to control with chemicals or other methods because they are protected inside the bud. The most effective time for control is during the relatively short emergence period which is difficult for growers to predict. The key objectives of this study were to monitor mite emergence from big buds in spring, determine the phenology of mites in relation to tree phenology and weather, and identify the optimum timing for control measures. Mite emergence was found to occur between early and late spring in Canterbury, New Zealand. Mite emergence and movement occurred when daily maximum temperatures were >15 degrees C and when mean temperatures were >9 degrees C, with mite emergence increasing with temperature. The developmental status of new buds during mite emergence was a crucial factor in the infestation of new buds. An accumulated heat sum model (DD), starting at Julian date 152 and using a lower threshold temperature of 6 degrees C, predicted the onset of emergence on two cultivars and at two sites at approximately 172 DD. A regression model based on leaf number, bud length, bud width, DD and Julian date provided a more satisfactory prediction of percent accumulated mite emergence. It is recommended both peak mite emergence and the developmental status of hazelnut buds be used to optimise the time to apply control measures. The optimum time to apply a control was predicted to be before buds measure 0.5 x 0.5 mm (width x length), are enclosed within the axil, and have a rounded tip, or, when 50% accumulated mite emergence has occurred, whichever occurs first.
瘿螨是全球榛树的主要害虫，但由于它们受到芽的保护，因此很难用化学药剂或其他方法进行防治。防治的最有效时间是在相对较短的出蛰期内，而种植者很难预测这一时期。本研究的主要目的是监测春季瘿螨从大芽中的出蛰情况，确定瘿螨物候与树木物候和天气的关系，并确定防治措施的最佳时机。研究发现，在新西兰坎特伯雷地区，瘿螨出蛰发生在早春到晚春之间。当每日最高气温>15℃且平均气温>9℃时，瘿螨会出现出蛰和活动现象，且瘿螨出蛰数量随温度升高而增加。瘿螨出蛰期间新芽的发育状况是新芽受侵染的关键因素。一个从儒略日152开始、采用6℃较低阈值温度的积温模型（日度）预测，两个品种和两个地点的出蛰开始时间约为172日度。基于叶片数量、芽长、芽宽、日度和儒略日的回归模型对瘿螨累计出蛰百分比的预测更令人满意。建议同时利用瘿螨出蛰高峰期和榛树芽的发育状况来优化防治措施的施用时间。预计施用防治措施的最佳时间是在芽的尺寸达到0.5×0.5毫米（宽×长）之前、芽被包裹在叶腋内且芽尖呈圆形时，或者在瘿螨累计出蛰达到50%时，以先出现者为准。
