Sad tomatoes

Asked July 16, 2018, 10:30 PM EDT

3 of my 8 Tomatoes look like the attached. Can you tell me what is causing it? They are all different varieties. I am wondering if it will effect the other tomatoes if I leave them in the ground.

Washington County Oregon herbicides abiotic issues tomatoes

1 Response

Your images clearly show that your tomatoes have been affected by herbicide (weed killer).

Such damage can occur in several different ways:

(1) Herbicide was sprayed nearby, possibly even next door. Spray readily moves with a light breeze and can damage sensitive plants such as grapes and tomatoes; (2) The tomatoes were sprayed for either insects or disease but was applied with equipment which had previously been used for weed killer. (Unfortunately, the residue never washes out completely.); (3) Herbicide carryover in organic matter such as manure, composted or not.

Herbicide carryover may occur in manures. It is well explained in this Q&A written for gardeners and farmers shortly after the problem was first described in 2005. (https://s3.wp.wsu.edu/uploads/sites/411/2014/12/Paper_Clopyralid_QandA_v10.pdf)

If manure (composted or not) was applied to the garden, you can verify if it is the source of the distortion with a simple bio-assay in which you plant a few seeds (radishes or peas) and wait to see if they sprout; if they do, are the plants normal? (Details of the bio-assay are here https://s3.wp.wsu.edu/uploads/sites/411/2014/12/PDF_Clopyralid_Bioassay.pdf.)