Question
QUESTION: So my sister decided she wanted to grow some tomato plants. She had been doing really well with them up until the miners showed up. She thought it was a fungus, so she had been trimming the infected leaves off, but it's still there. We did some research (aka Google) and found out that you can use insecticides and neem oil and plastic mulch to combat it. My question is, what is the best method of killing these things? Also, does neem oil actually work? It sounds kinda iffy. We really wanna use insecticide as a last resort since that stuff is expensive and the plants are still in pots.

Thanks!

ANSWER: Brittany,

Where are you growing these plants, in a greenhouse, indoors? Could you post a picture of the leaves so I can be sure it is leafminers? Post a follow up and I'll help you figure this out.

Jack DeAngelis
http://www.livingwithbugs.com



---------- FOLLOW-UP ----------


Leafminers?   QUESTION: She's growing them in pots inside the house but she does take them outside to get some sun. Just took some photos of them with my camera. Hopefully these will be good enough. Let me know if you need more pictures.

ANSWER: Brittany,

You're right this is a serpentine leafminer. The mines are caused by the larva of a fly that burrows inside the leaf. These flies are important pests in greenhouses on vegetable plants and flowers. It is unusual to have an infestation of these flies in a house, however. Are you growing these tomatoes from seed or starts? At any rate the best insecticide, and also one of the safest, would be spinosad (see http://www.livingwithbugs.com/spinosad.html for a factsheet and label). The other option would be to discard all plant material, wait a few months for the flies to die off, then start over and grow your plants only from seeds. I suspect that the original infestation came on plants brought into the house.

I hope this is useful.

Jack DeAngelis
http://www.livingwithbugs.com



---------- FOLLOW-UP ----------

QUESTION: Thanks for the information. This is Brittany's sister. I actually grew them from seeds. After they sprouted I transferred them into pots. From there, I began leaving them outside for a few hours so they could get used to being outside before transfer into the ground, and for sun.(plenty here in sunny Florida) I think I might have brought them in from when they spent their first few trips outside, other than insecticide to beat back the infestation, is there anything else you would suggest to help out? I thought mulch and selective pruning is supposed to help out as well? I'm asking because the infestation has gotten pretty bad, as I was unsure of the cause, and it's gotten to the point where it's stunting the growth.

Thanks in advance,
Bre.  

Answer
Bre,

The infestation must have originated outside, perhaps from a nearby agricultural field or greenhouse. Often young plants will outgrow the damage if given good growing conditions, water and fertilizer. Certain reflective mulches have been used in large agricultural fields but they won't work in this case. Selective pruning probably won't help either because the infested leaves are going to drop off anyway. I'd suggest just trying to give the plants good growing conditions and hope for the best. If you decide to try this again I'd suggest getting some grow lights and keeping the plants indoors under the lights until they are ready to transplant outside.

Good luck.

Jack DeAngelis
http://www.livingwithbugs.com