2. Materials and methods
2.1. Plant materials
Twenty-one randomly distributed trees of guava cv. Allahabad
Safeda of uniform age and vigour were selected at Punjab
Agricultural University Regional Fruit Research Station, Baha-
durgarh, Patiala, India. These 10 year old trees, trained according
to the modified leader system, were maintained under a
recommended schedule of fertilizer, irrigation and phytosanitory
treatments for insect pest control (Punjab Agricultural University
Recommendations). The hexanal stock formulation (EFF) was
made as per protocols described by Paliyath and Murr (2007) and
included1% (v/v) hexanal, 1% v/v geraniol, 1% (w/v) of alpha-
tocopherol and 1% w/v of ascorbic acid, and 10% (v/v) Tween 20,
dissolved in ethanol (10% v/v). Essentially, a stock solution was
prepared by mixing the ingredients with stirring and dilution to
1 L with distilled water.Prior to spraying, stock solution was
diluted with water (1:100; 1:75; and 1:50) and mixed by
agitation to provide treatment levels of hexanal ranging in
concentrations from 0.01%v/v, 0.015% v/v and 0.02% v/v in the
final spray solution. Molar concentrations of hexanal in the
final
solutions used for spraying were 0.8 mM, 1.2 mM and and 1.6 mM,
respectively. Diluted solutions appeared light milky white and