have a couple choices. I thought about solarizing the area they are in only, but not sure if it will go deep enough. We will have a good month of HOT weather yet this year. Then
take it off and recompost ot help the soil recover.
Second is to drench the area with homemade catille soap water.
Third is to drench the soil with garlic/hot pepper water with sesame oil mixed in.
Fourth is to mix boric acid and sugar and put it in the garden, although I am concernced about toxicity to us if ants carry it to roots of plants.
Spring next year we are going to be ready and attack the ants while they have hills everywhere.
Which is the most effective while being least harmful to the soil, and to us? Or even combination of more than one. Thanks
Also, get some ladybugs.
No crop or animal can survive if its food source and appropriate habitat is not present. I tend to look at insect pests as at weeds: when they are present it means there is a food source and a habitat. When they are present in overwhelming numbers and are not being controlled by something else there is a food source imbalance. Killing the pest, whatever it is, will NOT restore the imbalance and you will have to kill it every time it comes back until eternity.
You would look first at providing a habitat to the pest predators (their food source being available). If you kill the aphids the ants will refarm them and it's only a matter of time before they farm them in big enough numbers to become a nuisance again.
In killing the aphids or the ants you will have broken the natural cycle of waiting for the predators to come on. If the predator habitat is available (and in most permaculture gardens with their varied landscapes that is not a big problem), the abundance of pests will have attracted predators who have been busily laying eggs. If the eggs hatch after you've killed the pest off the predator larvae will not find food and die. Vicious circle.
Give it a season. Farm whatever you can in spite of the pests. Provide an abundance of predator habitats: stones, wood, hollow reeds, trees, bird houses, tangles of vines, growth of various sizes, a little pond, and become the observer... You will learn many things about sustainability this way...
All the best...
Before you do anything, look more closely. Are all the plants equally infested or are there some with no or fewer aphids? If there are, you can take some leaves from one of those plants, mash them up a bit and put them in some water and leave it all in the shade for a couple of days, then strain the result and spray it on the affected plants. Another thing to try is get some seaweed solution and water the affected plants with it. Neither of these should harm the ladybugs.
Next, simply be patient. If there are huge numbers of aphids you should soon have larger numbers of aphid predators. So many even the ants wont be able to fend them all off.
Longer term solutions:
1. Add more minerals to your soil. An aphid infestation means that your plants are lacking in "minor" minerals. Packaged soils (in my experience) are often lacking in this way. In most parts of the country it doesn't matter, since plant roots can find some minerals from the native soil. But where the native soil is either total sand or very low on minerals from high temperatures and lots of rain, the plant roots cant find all the minerals they need. In the past I used pulverized granite and it solved the problem, but I can't find it for sale any more. I did just buy something called azomite but I haven't had it long enough to know if it will work equally well.
2. Make a place for weeds in the garden. Right now I have some dandelions covered with aphids and no aphids on my veggies 3 feet away. By keeping weeds growing around the garden, the aphid predators have a home and food all the time. Designate a spot or two for weeds and just let whatever comes up grow there and water it along with the garden. I know, it seems wacky to purposely grow weeds, but I've been doing it for years and my garden is healthier for it. Every so often, turn the weeds under or pull them off and compost them or use them for mulch. If you use them for mulch around your veggies, pull them before they make seeds. If no weeds want to grow on their own, you can get seeds of dandelions and some other barely domesticated greens and plant them.
3. You only mention tomatoes, so I don't know what else you might be growing. If it is only tomatoes, that is a monoculture and that is part of the problem. Try planting some black-eyed peas beside the tomatoes (they love the heat). You can get a bag of them from the grocery store (if they carry them) and plant them or buy seed which is more expensive. The black-eyed peas will feed the tomatoes as well as create greater diversity. If you dont want to eat the peas, cut down the plants right after they flower and plant more. You can lay them on the soil around the tomatoes as a mulch.
4. Do everything you can think of to increase the life in your soil. Make compost - as hot and dry as it is there, I would think pit composting would be the best bet. Dig a hole and put vegetable matter in it. Since your soil is pretty sterile you probably need to add compost starter. Keep it moist (you can pee in it) and shaded. Add some potting soil that has live microorganisms in it. Maybe add earthworms if they don't show up on their own. When the hole is filled with finished compost, plant in it.
One thing that would help with your water use would be to line your planting holes with something that would retard the escape of water. Water in sand tends to go straight down more than fanning out sideways. I wonder if putting a large rock or stepping stone in the bottom of the hole would keep water from escaping. Mulch on the top of the soil will keep water from evaporating upward. Generally I don't like to use plastic in gardening, but I wonder if plastic mulch (the kind with breathing holes) lining the sides of the hole would decrease the need for water. You could also use a layer of clay to make a sort of on-the-spot pot which would hold back water and give the plants minerals at the same time. The only source of clay I can think of is pottery clay and I'm not sure if it has any minerals that could be toxic. How about burying large terracotta pots and planting in them? Probably expensive. I'll be gardening in Florida sand in a few years as opposed to worn out Savannah, GA soil so I've been giving these things some thought.
If you research root aphids, they are at the roots. All the great bugs that were are in my garden who have kept there from being any aphids above ground until now, could do nothing for all the aphids below the ground. The ants are causing that issue. if I want to take up their food source, I pull up my crops. Pass on that. I have already lost quite a bit. ALmost all of the beans in those areas.
Can anyone answer the question of which method is the least harmful, instead of whether I should target the ants and root aphids.
Alternatively, let the pigs loose and do the same thing, too long or too many.
Or, put a very large amount of compostable material right over top of an anthill and watch it cook.
Of your choices, I'd pick boric acid and sugar, but only around the anthills.
Just my opinion... Good luck.