Hevea brasiliensis natural rubber production is strategic for the world economy. Meloidogyne exigua causes the main root disease in this crop in Brazil. Its early diagnosis allows better pest management, reducing losses. This study aimed to identify rubber tree orchard areas infested by M. exigua using remote sensing and vegetation spectral indices—normalized difference vegetation (NDVI) and simple ratio (SR)—generated from the RapidEye^® satellite constellation images. Orchards under tapping in Minas Gerais state (irrigated) and Goiás state (without irrigation) were sampled during the rainy season and soil, root and total nematode density were estimated. Although significant interactions between nematode density and vegetation spectral indices were found, none had determination coefficient (R²) greater than 0.31. Descriptive statistics of both orchards did not identify differences between the areas and root or total nematode density; however, nematode density in the soil in the Goiás orchard was 236% greater than in the Minas Gerais orchard, while both spectral vegetation indices were lower in the former. Such differences might be a consequence of irrigation. Pearson’s, Spearman’s and Kendall’s correlations between nematode density and NDVI presented greater coefficients than SR for every parameter in both orchards. NDVI can be used to distinguish non-infested rubber tree orchard from one infested by M. exigua.

中文翻译：

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利用卫星图像获得的植被指数检测南方根结线虫感染的橡胶树果园

巴西橡胶树天然橡胶的生产对世界经济具有战略意义。南方根结线虫是巴西这种作物的主要根系病害。它的早期诊断可以更好地控制害虫，减少损失。该研究的目的，以识别由侵染橡胶树果园区域M.夜蛾从RapidEye -生成利用遥感和植被光谱指数-归一化植被（NDVI）和简单的比率（SR）^®卫星星座图像。在雨季对米纳斯吉拉斯州（灌溉）和戈亚斯州（未灌溉）下的果园取样，并估算了土壤，根和总线虫密度。尽管发现线虫密度与植被光谱指数之间存在显着的相互作用，但没有一个具有确定系数（R ²）大于0.31。两个果园的描述性统计都没有发现面积与根或总线虫密度之间的差异。然而，戈亚斯果园土壤中的线虫密度比米纳斯吉拉斯州果园高236％，而前者的两种光谱植被指数都较低。这种差异可能是灌溉的结果。对于两个果园中的每个参数，线虫密度和NDVI之间的皮尔逊，斯皮尔曼和肯德尔的相关性均比SR高。NDVI可用于区分未受侵染的橡胶树果园和由莫桑木分枝杆菌侵染的果园。