In Agrobacterium mediated transformation applications Silwet l-77 is typically used in 0.01%-0.02% (v/v) range. This concentration is sufficient to break the surface tension of water and allow for film formation ensuring good penetration of you extracts in to the plants.

Your dilution 3 ml in 500 ml is 60x that concentration. Silwet, as are most surfactants, can interfere with cell membranes (this is one of the reasons why surfactants like SDS and Tween-20 are added to protein and DNA isolation buffers).

Therefore, I would not be surprised that the high concentration of Silwet in your spray ends up having detrimental effects on your vegetables. I suggest using 0.01%-0.02% of Silwet.

Thank you very much for your response,

It is so helpful. Yes I am using high concentration.