Studies on Root Knot Nematode (Meloidogyne enterolobii) of Guava

Abstract

Guava is a native of America and introduced into India during 17th century. Guava is cultivated worldwide due to its adaptability and survival ability in subtropical and tropical countries. India is the largest producer of the guava in the world with an area of 307 thousand hectare and production of 4516 thousand metric tonnes. In India, Uttar Pradesh has maximum production of guava 983.59 thousand tones and area 52.25 thousand hectare. In Uttar Pradesh, Allahabad is the largest producer of guava with maximum area under cultivation. Guava root-knot nematode, Meloidogyne enterolobii is a newly emerging pest of guava. This study presents comprehensive research on various aspects of guava root-knot nematodes, including survey in major guava-growing districts, molecular characterization of the nematode species infesting guava, evaluations of novel nematicides and bio-agents, and integrated management strategies under controlled conditions. Survey was conducted in 17 districts of Western Uttar Pradesh to know the status of root knot nematode in the guava orchards. The survey results revealed that the L-49 guava variety is most common among farmers. Through survey incidence of guava root knot nematode was recorded ranging from 12 to 72 %. Whereas, prevalence was recorded from 40 to 90 % in the surveyed area. Nursery survey was also conducted in Meerut and Amroha district to know the status of nematode infestation in guava nurseries. On the basis of survey it was recorded that all the nurseries were infected by guava root knot nematode. Pathogenicity test was also conducted to test the role of M. enterolobii in cause root knot in guava. Through molecular characterization using ITS universal primers, confirmed the presence of M. enterolobii in surveyed samples, with high nucleotide homology. Commonly available varieties of guava were also tested to know the response against root knot nematode. All the tested varieties were found susceptible against root knot nematode. To know the host range 12 different hosts were also tested against guava root knot nematode. Out of 12 host 5 (Okra, Chilli, Cranberry, Lemon and Pear) were found as non host. A pot experiment was conducted to check the efficacy of bio-agents in which six bio-agents were applied. After 6 month of transplanting minimum (11.66 galls/5g of roots) were recorded in Trichoderma isolate S-13 and maximum (49.33 galls/5g of roots) were recorded in Pseudomonas fluorescens. Similarly after 9 months of transplanting minimum (21.66 galls/5g of roots) were recorded in Trichoderma isolate S-13 and maximum (66.00 galls/5g of roots0 were recorded in Pseudomonas fluorescens. A pot experiment was conducted to check the efficacy of nematicides in which three nematicides in two different doses were applied. After 6 and 9 months of transplanting fluopyram 34.48% SC was found very effective to control the M. enterolobii and Carbofuran 3% CG was found less effective. To check the efficacy of combinations of oil cakes and bio-agents a pot experiment was also conducted in which ten combinations were applied. After 6 months of transplanting minimum (28.66 galls/5g of roots) were recorded in Neem cake + Trichoderma whereas maximum (50.33 galls/5g of roots) were recorded in Mustard cake + Pseudomonas fluorescens. While after 9 months of transplanting minimum (38.33 galls/5g of roots) were recorded in Neem cake + Trichoderma and maximum (66.33 galls/5g of roots) were recorded in Mustard cake + Pseudomonas fluorescens. This research contributes valuable insights into the challenges posed by guava root-knot nematodes and provides potential solutions for mitigating their impact on guava cultivation in India.