tomatoes and Irises - Knowledgebase Question

kalamazoo, MI
Question by dfgquilter
August 1, 2007
Hi., I have some worms in my cherry tomatoes this year. What can I spray on them that is safe for humans?

Irises.. you said I can move them. When can I cut them down to little fans? Do they have to be 3/4 yellow on the leaf?

thanks, Dorian

Answer from NGA
August 1, 2007


Fruitworms: At hatching, tomato fruitworms are creamy white with a black head and conspicuous black hairs but as they grow larger they range in color from tan to yellowish green to pink to nearly black and develop fine white lines along the body. They eat holes in fruit, but rarely damage leaves. Young worms enter green fruit at the stem end and may emerge from one fruit and enter another. Their feeding results in a messy, watery, internal cavity filled with cast skins and feces. Damaged fruit will ripen prematurely. Both the worms and moths are about an inch in size. Adult moths are pale tan to medium brown colored or sometimes have a slight greenish tinge. They lay their single eggs on either the upper or lower leaf surface.

Bacillus thuringiensis spp. kurstaki is sold under many trade names like Worm Ender, Caterpillar Killer, Dipel, etc. This material may be less effective than some broad-spectrum insecticides, but it does not destroy the natural enemies of tomato pests. Apply when worms are small, not large. Bt products are highly effective against hornworms and slightly less effective on fruitworms, armyworms, and pinworms because worms must eat it and hornworms eat more foliage than the other fruit boring worms. If the plants are growing vigorously several applications may be needed.

Another soft insecticide contains the active ingredient, spinosad, which is a naturally occurring organism synthetically manufactured by fermentation and sold under several trade names. Spinosad has a unique mode of action different from all other known insect control products, which are more harmful to humans. Spinosad works by contact with the insect and more effectively by ingestion as insects feed on the foliage.

Don't reach for the spray bottle immediately. If only a few tomatoes are damaged, then pick the solid ones and leave the wormy ones outside.

You can cut your irises down now and replant them. The foliage does not need to be 3/4 yellow.

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