We had probably one of our very best speakers of the year last Saturday at the Garden guild meeting. Sam Slaughter from Gabriel Valley Farms spoke to us on organic pesticides at the meeting. He was incredibly knowledgeable and it brought sheets for us to take notes on that had all the different categories of pesticides that he discussed.
He stressed at the very first thing you needed to do was identify what the pest was that you were wanting to treat or eliminate. You can do a web search looking for pictures or images of the pests you have found, take a picture of them with your camera or phone, and ask the county extension office to help you identify what the pest is. Once you've identified the pest then decide how aggressively you want or need to treat for this particular pest. Sometimes you may want to use a trap, just hose them off with a stream of water, or pick them off by hand. You may also want to promote beneficial insects in order to control the pests. Some of these are ladybugs and lacewings or special companion plants that serve to deter pests. If you are going to use beneficial insets remember that many of the pesticides will kill them as well so introducing ladybugs and then spraying with the pesticide is not in an effective way to manage the problem.
Next he talked about a broad spectrum organic pesticide called spinosad. This is found in several other products as well as a product in its own right. Oils that can be used in the garden are listed as neem oil, cinnamon oil, orange oil, and karaja oil. He said it is more a presence and aroma thing and they are all about as effective as each other. They are surfactants that clog up the thorax of the insects they are fairly general i.e. not specific to anyone one pest. It is best to use them in the evening as they have about a 24 hour lifespan and most of them need to be used under a temperature of 92° and when it is not sunny to prevent burning of the foliage of the plants.
There are number of soaps on the market that are specifically organic one is safer soap a second one is Desex. You can also use Castile soap, Ivory soap but detergents like Dawn are not organic.
He also talked about pyrethrins which come from a specific Chrysanthemum. This is a much older class of organic pesticide and is a neurotoxin to the bugs but not to people. The lifespan of these also is about 24 hours give or take. They are great to use on aphids one time. It seems that the pests that are not killed off the first time around develop a resistance to the pyrethrins and need to be treated with a second products to eliminate them. Perhaps a really bad infestation of aphids can be treated with pyrethrins then after about 48 hours ladybugs released to take care of the remaining infestation.
He also discussed diatomaceous earth. it's great for deterring ants. it's a contact dust so if you're sprinkling it around you should be wearing a dust protective mask to not get it inside your lungs. If it gets whetted it becomes ineffective. Sam talked about using sticky cards in the garden and was telling us that there are a lot of them now that have specific pheromones on them to attract just the pest that you are trying to eliminate instead of wide swath of them.
We also talked about Bacillus thuringiensis or BT one of the products on the market is called dipel. It is a stomach poison specific for caterpillars but it will kill all kinds of caterpillars including the larvae of any butterflies that you're trying to attract to your garden. This also should be used in the evening to treat the plants but it takes 2 to 3 days to kill off the caterpillars. You might have to retreat because some of them had not hatched yet when you treated the first time. There is a product on the market for grasshoppers called Nolo but it treats juvenile grasshoppers not adults. Sam says garlic and pepper spray on the foliage is fairly effective as well.
There are new biologicals being developed that are just coming out on the market commercially they are fairly broad. one is called Preferal the other is called Mycorral trawl they actually are a living fungus that you spray onto the leaves they last for several days and they are trying to specific size them as they are being developed.
We also discussed killing weeds naturally and talked about the vinegar and salt treatment for weeds there are several variations on this listed on the Internet the product not to add to this blend is Epsom salts it is a folio or you can use orange oil in it you can use Nemo oil in it you can use the vinegar and it's sunny days are the very best and retreatment will be required because you're killing the foliage and not the roots. If you're pouring this on the soil the salt may prevent anything else from growing in this location for sometime to come.
We also talked about ways to treat poison ivy and other poison exposures from that family including feels Napfor soap Ivory soap which both defat the skin there a number of products to treat your reaction once you at once you've been exposed. We also discussed that under no circumstances are the plants to be burned as it can cause your hospitalization.
In the Q&A's we talked about crown disease in cotton and lavender and the need for a root shod that is a living fungus to protect it. For powdery mildew on peas and other plants use oil spray regularly to prevent it. For trees like crepe myrtles it may be as important to adjust the sprinkler heads and promote air circulation as to treat. For leaf miners and shot holes in leaves use oil sprays too.
Sam has invited us to come out to his nursery for a tour and I believe that George Holcomb will help us organize this trip later in the year.