Yourmomm
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Neem oil vs soap?

Hi all,

I've been advised that my tomato seedlings probably have an insect infestation which is damaging to their leaves, and that I may need to treat them.

Has anyone got any thoughts about the relative pros and cons of treating this sort of problem with neem oil, vs soap? I am trying to grow organically, and (as a result) have had tomatoes fail on me, for four years in a row. This year WILL be different!

Yourmomm
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Forgot to say that I was thinking about neem oil, instead of soap, as it's been warm and wet here so far this year, and I'm not convinced the problem isn't a fungal one, yet (cant find any evidence of insects)...

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digitS'
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I'm not sure what to say. My location is dry, with summer afternoons often having below 20% humidity.

I have had some problems with neem oil and damage from sunlight. I also didn't have any real success with it against powdery mildew. It has killed aphids well.

Dish soap probably can't really count as organic, although plenty of people are using it to clean eating utensils. I have also found that plants can burn after being sprayed with dish soap. It kills aphids and spider mites.

I am more comfortable using insecticidal soap and it doesn't seem to set the plants up so much for sunburn. I don't believe it is recommended for any fungal diseases. One thing that I have done with dish soap is wash the plants with the hose in the early morning after spraying. I try to never spray any pesticide in the garden until late afternoon.

Steve

Yourmomm
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Thanks Steve. I will follow your advice. I especially appreciate the advice about sunburn, as I'm suffering with this on the leaves, even before I've treated with anything...

imafan26
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You should try to identify the problem first.
insecticidal soaps and oils only work on soft bodied pests like aphids and mealy bugs and scale crawlers, not so much on the adults.
Hot dry weather and russeting on the leaves are usually a mite problem and soaps and oils are not the best solution since they are hard bodied spiders. You need a miticide for that. If it looks like the leaf is etched or scratched with light areas, it is likely to be thrips, who are a problem in hot dry weather. However, most miticides and more toxic insecticides kill good bugs as well as bad ones and you end up with more trouble down the road.
Any oil in hot weather can burn a plant especially if you get 90 degrees or higher.
Neem can be a preventive fungicide it does not work very well as cure. To tell the truth, fungal disease is difficult to control with any topical product and you don't really want to use a systemic on an edible plant.

I commend you for trying to be organic, however, trying to grow tomatoes organically in small pots are probably why you are having issues. The seedlings are probably not getting enough nitrogen and that weakens them. Weak plants are good targets for insects. You have to make sure if you have pest problems especially in a nursery or indoor location that you thoroughly sanitize the area before you bring more plants in and sanitize the area on a regular basis with every rotation. Otherwise the bugs will be there when you bring them their next meal.

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KitchenGardener
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What kind of sanitizing practices do you recommend, imafan?

imafan26
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Just a thorough cleaning. In a greenhouse it means, taking everything out and bleaching or using physan on the benches and floors. Usually, all plants that come in need to be in new soil and carefully inspected to make sure no bugs are coming in with them. Seedlings don't recover well from early bug problems and do not perform well in the long run, so unless problems are dealt with quickly, it can spread like wildfire and is best to start over.
Indoors it means cleaning the walls and floors with a disinfectant. You can use 1 part bleach and 4 parts water. Make sure it is safe for the paint. Pay attention to the joints and corners that is where the bugs like to hide. If the floor is relatively dry you can put diatomaceous earth around the perimeter. Make sure you wear a mask and it works better if you have a duster to direct where the dust goes. I was lucky, I found a duster locally. I had not seen one in years. I usually wait 2-3 weeks before restocking plants to either kill off or wait for the bugs to go leave and look for greener pastures.

You don't say where you live. If you are growing tomatoes,select varieties suitable for your area. Start with the easy ones like the cherries. Temperature minimum is 50 degrees but they do better at 70 with a heat mat. Tomatoes are heavy feeders and hard to start and stay in small pots for more than a couple of weeks after germination without adequate nutrition. They need to be planted out quickly if you want to try to grow them organically and you will have to supplement with weekly fish emulsion. You would need a 26 gallon container to grow anything organically sustainably and that would only be if you have a healthy soil web in that container to support the plants.

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Gary350
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You need several small birds and bugs that eat other bugs. I use to have 25 bird houses but now I only have about 14 houses. Wrens are known to eat their body weight in bugs every day. If you see a spider in the house, garage, shed, etc, move it to the garden. I spray the underside of my tomato plant leaves with a hard water spray with the garden hose it blows the tiny mites and aphids away. Get a weed spray tip like they use on farm equipment attach it to your garden hose it only needs to sprays a very small amount of water about 1 gallon of water per hour this is enough to blow small bugs away if you hold the sprayer 2" from the leaves. When mites and aphids get bad in my garden the last week of July to Sept I have to spray the under side of my tomato plant leaves about 3 times a week for bugs to be gone. Once mites and aphids get started eggs hatch out on the leaves. Another things that works for me is rub tomato leaves with your finger it smashes the bugs dead. If you plant tomatoes in full hot sun that reduces bugs but tomato plants do not like the hot sun.

imafan26
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PS. Neem is very popular, but I rarely use it since it gives me a headache. I do use a blast of water under the leaves and look at them every time I water. I prefer to use just plain 70% alcohol straight from the store with a sprayer attached to the bottle, most will fit but you may have to cut the tube if it is too long. Just don't spray in the heat of the day. It takes care of most problems and usually does not affect beneficial insects very much since it is a contact spray.

Birds in my neighborhood are more fruit and seed eaters and will actually eat my tomatoes and peppers if they are not covered with bird netting. The birds also like young lettuce leaves. The cattle egret does eat insects but it is a foraging bird and usually shows up after the grass is cut. It will also eat lizards, skinks, and geckos which are my main caterpillar, beetle and unfortunately earthworm eaters. Spiders also trap some flying insects. I do have a problem with white peach scale, they are immune to just about everything so I just use a brush dipped in soap and water and scrub them off to keep them in check. I don't really want to get rid of my 10-20 year old roses. I have orchids, plumeria, gardenia, and jasmine sambac which are thrip magnets. I don't want to get rid of the plants, so I just live with them Anything I use will also kill predators. I do plant nectar and a variety of flowering plants to attract beneficial insects. White flies are attracted to the hibiscus, so I use it as a sentry plant. I spray that plant when it is not in flower and I cut it back to the ground and bag it when it is heavily infested. That way, the white flies more or less stay off the peppers (I water under the leaves every time I water). Right now, the hibiscus is clear and I have gotten most of the host weeds near it out. I usually plant corn in summer and that will attract the purple ladybugs that eat the white flies. I have male fruit fly lures in the front yard and I need to refill them. I did have some issues with the melon fly stinging my cucumbers but it resolved when I got rid of the old beans, zucchini, and cut back the ti plants. I did not have to use the GF 120. In April, I will have to treat another hibiscus (modern hybrid) for erineum mites with a systemic. It is a legacy plant I don't want to get rid of. It is in a pot and in the ornamental part of my yard.

I know my pests and try to use the least toxic means to control them. Because I do not spray regularly and grow a variety of flowering plants to attract beneficial insects, most of my pest problems are minor. I haven't seen an aphid except on the citrus for years. The other pests are usually treated with blasts of water, baits, bagging, roguing out sick plants and hosts, alcohol, and allowing the beneficial organisms to keep their numbers down although they never will be zero.

Slugs and snails are a different matter, the birds and rats eat the slug bait and I don't have a chicken, so they are winning. I catch about 6-7 every day. I got 32 one morning after it rained.

if you are growing your plants in good conditions and they are happy, they attract fewer pests. Inspect your plants regularly, feed, water and up pot as needed. Make sure they get good air circulation and you keep up with the sanitation. You will find you have the same pests and once you figure out what they are and work out a way to break their cycle it will be easier to keep ahead of them.



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