Expert: Mike Mascio - 7/30/2006

Question
Zone 6  Brooklyn, New York

Mike,
My petunias are the beautiful cascading "Easy Wave Blue" variety growing in a container on my back porch, getting full sun. I would like to know how to prevent the catapillars from occurring and eating my petunias. (An age old problem-indicative of petunias?) I assume they occur from moth larva? I tried dusting the petunias using SEVIN-5 by GardenTech, but I'm still painstakingly finding them daily when deheading.  They range from micro tiny to about an inch, they are bright green. I look for their droppings or the holes that they bore into the new forming buds and flowers that are about to open. My plant is not infested, but it is annoying! I like my petunias to look perfect!   Will I ever be able to achieve this or do I have to share my petunias with this pest?  None of my other flowering plants have any pests!

Thank you for any advice you suggest.  

Answer
Kate, it sounds like your petunias have been infested with green hornworms. Hornworms are actually small caterpillars that chew large holes in the leaves of tomatoes, eggplants, peppers, petunias, and potatoes. Their young larvae are white but they eventually mature into a deep green that blends in with the foliage making them hard to detect.

You can control them by hand-picking them or using an organic dust control called BT (bacillus thuringiensis), more commonly sold under the product name Dipel or MVP. BT is non-toxic to humans, pets, and the environment, and can be applied right up to the time you harvest on vegetables, and anytime on annuals. You can purchase these products at a local garden center or through an on-line catalog such as Gardens Alive at:

http://www.gardensalive.com

I hope this answered your question. Good luck, and please write again if I can ever be of assistance.

Regards,

Mike