Relationship among the potato rot nematode, Ditylenchus destructor, densities in soil, root and garlic (Allium sativum) bulbs, and rot damage in stored garlic bulbs

Abstract

Summary The potato rot nematode, Ditylenchus destructor , threatens garlic production in Japan. The objectives of this study were to determine the relationships of D. destructor densities in soil, garlic roots and outer skins of garlic bulbs, and damage to bulbs that rot during storage. Ditylenchus destructor densities were evaluated with the real-time PCR method. There was a significant positive correlation between D. destructor densities in soil at planting and those in the outer skin of garlic bulbs at harvest in 2016, but not in 2017. Ditylenchus destructor densities in outer skins at harvest were consistently low when those in roots at harvest were lower than 80 ind. (0.05 g) −1 . No damage to garlic bulbs after storage was observed when D. destructor densities in outer skins were lower than 300 ind. (0.05 g) −1 . These results indicate that D. destructor densities in roots and outer skins may be a good indicator to estimate nematode damage to garlic bulbs after storage.