Issue: December 30, 2006
Stopping pyracantha from making fruit
Is it possible to sterilize pyracantha plants?
You didn't explain why you want to "sterilize" your pyracantha plants. I assume you don't want to kill the plants, but you don't want the fruit and perhaps you don't want the flowers.
I have often received the opposite question when people want to be assured that their pyracantha plants will produce fruit. The answer to their question is often not to prune between late summer and spring. As I answer your question I will reverse the recommendation.
The pyracantha plants flower in the early spring. That means the flowers were formed during the late summer and overwintered in the buds. Pruning during the winter will remove many of the flower buds. This will reduce the production of flowers and fruit the next year. (Readers who want the flowers and fruit should do any necessary prune after flowering, but don't remove all the newly formed fruit when pruning.)
Even after pruning in the winter, there may be some flower buds that remain on the plant and some fruit may be produced. These can be pruned off while in the flower stage, or the developing fruit may be pruned afterwards.
If you don't mind the pyracantha flowers and just don't want the fruit produced, there is a product that will cause the fruit to drop after flowering. The product, Florel® Brand Fruit Eliminator, contains ethephon as the active ingredient. The ethephon releases the plant hormone ethylene which causes much of the fruit to fall from the plant. The manufacturer states that timing is critical to achieve optimum results. According to some garden writers, the ethephon must be applied immediately after flowering or during flowering. Ethephon is reported to have no insecticidal properties and doesn't harm bees. However, it does have herbicidal properties, so apply it according to the label directions on a windless day.
Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: firstname.lastname@example.org, office: 505-865-7340, ext. 113.
Please copy your County Extension Agent and indicate your county of residence when you submit your question!