The long-standing problem of guava wilt in Uttar Pradesh has worsened in recent years due to the spread of root-knot nematodes, a condition in which the roots of infected trees develop knots, due to microscopic multicellular organisms. Root-knot nematodes in UP guava (HT Photo) This significantly impacts orchard survival and productivity, scientists at the ICAR-Central Institute for Subtropical Horticulture (CISH), Lucknow said on Monday. According to PK Shukla, department of crop protection, ICAR, “Nematodes were introduced in India with the planting of Thai guava or Taiwan pink guavas in nurseries. From nurseries they spread to new locations.” He added, “These are parasites which attack plant roots after entering the roots, suck cell sap. Thus plant nutrition supply is interrupted and it becomes weak. In a few months the plant may die.” According to ICAR, while fungal wilt has affected guava crops for decades, the entry of root-knot nematodes into nurseries around 2014–16 aggravated the disease complex. These organisms spread rapidly through the major guava-growing region leading to declining yields and, in many cases, the collapse …