In vitro Evaluation on Efficacy of Bioagents and Plant Extracts against Early Blight of Tomato (Alternaria alternata)

AIMS: In vitro evaluation on efficacy of Bioagents and plant extracts against Early blight of tomato (Alternaria alternata)

Study Design: CRD (Completely Randomized Design).

Place and Duration of Study: A trial was conducted in plant pathology laboratory at HRS Venkataramannagudem, Dr. Y.S.R. Horticultural University, Venkataramannagudem, during 2022.

Methodology: The efficacy of bioagents were tested against isolates for radial growth inhibition on suitable media (Potato dextrose media and Nutrient agar media) using dual culture technique under in vitro conditions. The poisoned food technique was followed to evaluate theefficacy of botanicals in inhibiting the mycelial growth of test pathogen.

Results: In the present investigation total nine bioagents and four plants extracts were tested against Alternariaalternata under in vitro. Results revealed that among the nine antagonists., Trichoderma harzianum, Tichoderma viride, Tichoderma longibraciatum (TCT4), Trichoderma reesi (TCT10), A10 (Tichoderma asperellum), A28 (Trichoderma harzianum), Trichoderma virens and two bacterial bioagents Pesudomonas fluorescens and Baciilus subtillis tested against A. alternata, maximum reduction in colony growth of A. alternata was observed in A10 (T. asperellum) (69.50%) and significantly superior over all other bioagents tested which was followed by A28 (T. harzianum) (62.96%) and the next best was T. virens (60.28%). Least inhibition was noticed in Bacillus subtillis (46.69%). Total four plant extracts neem leaves (Azadirachta indica), onion bulb (Allium cepa), garlic bulb (Allium sativum), and turmeric rhizome (Curcuma longa) tested at three concentrations (5, 7.5, 10 %) with suitable control by poisoned food technique against A. alternata, onion bulb extract (44.07%) which was found superior to all other tested botanicals. Least mean per cent inhibition was recorded with turmeric (21.34%).