Effect of application of organic bio-products through drip irrigation against Tylenchulus semipenetrans in citrus

Field experiments were conducted to study the effect of different liquid bio-products such as neem seed kernel extract (NSKE), azadirachtin and humic acid delivered through drip irrigation system on acid lime trees naturally infested with citrus nematode, Tylenchulus semipenetrans. All the bio-products were applied at 4 L/ha twice at 30 days interval and their effect was compared with carbofuran 3G at 100 g/tree. All the tested bio-products significantly suppressed T. semipenetrans density in soil and acid lime roots. Among them, NSKE was superior that reduced T. semipenetrans population by 56.8–58.1% in soil and 46.4–56.2% in root. Azadirachtin was the next followed by humic acid. The effect of NSKE was comparable to the chemical standard check carbofuran in location I, but NSKE surpassed carbofuran in location II. Suppression of T. semipenetrans infestation and infection by NSKE lead to improvement in the number of fruits (21.3–22.3%) and fruit weight (17.4–20.8%) in acid lime trees. NSKE delivery through drip system resulted in 35.8–37.9% more fruit yield. The benefit-cost ratio was also higher in NSKE (1:3.7–1:4.8) where as it was lesser in carbofuran treatment (1:1.3–1:3.0).