Sunflowers and Spider Mites

13 years ago

Hi all,

My sunflowers have been thriving all summer long, but I noticed lately that some of them seem to have spider mites (or their tiny black eggs?) on the underside of the leaves. I've heard one can use a combo of dish-soap mixed with water to clean; and that this is better than the synthetic insecticides because the insecticides could harm the bees...and I've got tons of harmless bees who love my sunflowers(the house finches like them, too, btw!). But, I also read somewhere that one doesn't want to apply the soap and water on too hot of a day(like today), because that could harm the plant. So, I was thinking of waiting till later on this week when it's supposed to cool off a bit. Am I correct in my thinking or should I act immediately? Also, is it a good idea to 'rinse' off the soapy water mixture after applying it for a certain amount of time?

Any advice would be greatly appreciated, as usual! :)

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Comments (4)

lazy_gardens
13 years ago
Are the whatever they are causing the sunflowers any serious stress?

Plants will have bugs - unless the bugs are clearly killing the plant, don't do anything.

My eggplants leaves get chewed all to bits early in the season, but a bit later in the season the predators (birds, wasps, lizards) have wrestled things back into balance.

If I sprayed and killed the prey (food) the predators would be far fewer ... so I would have more damage than if I left it alone.
grant_in_arizona
13 years ago
Like Lazy mentioned, I generally try to just let things run their course--seems like once a plant has enough pests, someone finds out and eradicates them (hummers or ladybugs eating aphids, cactus wrens or wasps eating caterpillars, or parasitic wasps laying eggs in the caterpillars, etc), but even I have my limits, LOL.

If you decide to use a soapy mix or insecticidal soap, doing it in the evening is best so the plants aren't in the hottest temps and they're not in sunlight too much afterwards, and you don't want to wash it off as many of the soaps are designed to destroy the waxy coating on bugs and/or suffocate them so it's best to *not* wash it off after applied.

Some of my leafy annuals have had a very bad year this year with spider mites (tiny tiny red dots usually on the undersides of leaves or with webbing in the stem crotches), but things seem to be getting better now. I'm certainly not above using insecticides, but I only do it on hopeless cases and even then only on super sentimental plants, so it's a very rare occasion spaced by many years.

Anyway, let us know what you do and how it works out.
Take care,
Grant
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xica_da_silva
Original Author
13 years ago
Well, I guess the good news is, the plants are producing flowers, which is the goal, but the leaves are getting pretty discolored on the surface. I just noticed, too, that somethings been eating up the petals some of the flowers as well...it might just be the birds picking away at them to get at the seeds, though. I've got a lot of crickets in my yard...perhaps they are also in on the feeding frenzy? I'm inclined to let nature do it's job...but I just wish the ladybugs etc would hurry up before my poor sunflowers are completely ruined! I will try to be patient! Thanks for the advice once again Grant and Lazy...much appreciated.
aztreelvr
13 years ago
Sunflowers are a favorite of lace bugs. They have a piercing/sucking mouthpart like aphids and use it to sip fluid from leaves and stems. In the process they leave behind 'honeydew' which may appear as black dots.

These insects are facinating to look at under a hand lens. In large numbers they can impact the health of plants. The best way to discourage them is with a strong blast of water from a hoze nozzle. Hopefully an assortment of beneficial insects will find them before you need to resort to stronger tactics.

Good luck.

Here is a link that might be useful: Lace bug management guidelines