Squash and zucchini (Cucurbita pepo) crops require continuous protection against moisture-induced foliar diseases and blossom rots, including Powdery Mildew (Podosphaera xanthii), Downy Mildew (Pseudoperonospora cubensis), and Choanephora Wet Rot (Choanephora cucurbitarum). High humidity around dense bush foliage leads to flower rot and soft fruit tips, reducing marketable yield. Applying Bacillus subtilis as a preventative foliar spray or soil drench establishes an antagonist bacterial colony across leaf canopy and flower surfaces. The bacteria secrete cyclic lipopeptides (surfactin, iturin, fengycin) that inhibit fungal spore germination and stop hyphal expansion on tender blossoms.

Beyond disease control, Bacillus subtilis acts as an effective plant growth-promoting rhizobacterium (PGPR) in bush and vine squash crops. It solubilizes fixed soil phosphorus, mobilizes iron through siderophores, and secretes natural growth regulators that encourage rapid root expansion. Enhanced root mass supports continuous bush flowering, improves stem thickness, and produces firm, glossy zucchini and squash fruits. Regular application ensures residue-free harvests suitable for fresh green-market distribution.

Importance of Bacillus subtilis in Squash Cultivation

Squash is a fast-growing vine crop that requires continuous nutrient and water uptake from flowering until harvest. Healthy roots are essential for vigorous vine growth, proper fruit development, and sustained production.

Bacillus subtilis rapidly colonizes the rhizosphere and competes with disease-causing fungi and bacteria for nutrients and space. It also produces antimicrobial compounds that suppress harmful pathogens while promoting beneficial microbial populations.

Healthy root systems enable continuous flowering, improved fruit setting, larger fruits, and higher-quality squash production.