Friday, August 11, 2000
By Ken Sakamoto, Star-Bulletin
Healthy soil is an important factor in organic pest control,
according to Kimberly Clark, owner of Just Add Water
organic farm in Waimanalo. "If (your soil) is in balance
and you're getting the right nutrients, you have a good
healthy immune system."
This is an example of tag-team column writing.
In late March, Susan Scott's "Ocean Watch" column, which appears Mondays in the Honolulu Star-Bulletin, focused on the dangers of spraying the pesticide Diazinon, commonly used to control ants.
In particular, the chemical poses a hazard to plovers, those pretty, long legged birds that migrate through the islands and hunt for grubs on lawns around Oahu.
According to studies cited by Scott, ravens in Sitka, Alaska, recently died after application of Diazinon grass in their habitat, despite the fact that the chemical was used according to directions; in 1986, 54 fatal Diazinon poisoning incidents were described in 17 states among 23 species of birds.
Diazinon normally degrades rapidly, but in dry conditions it can remain active for up to six months, wrote Scott.
Plovers eat insects in grass for nearly eight months of the year in Hawaii, leaving in April and returning about now.
In the wake of Scott's column, many readers requested information about alternatives to this chemical pesticide.
Two out of two organic farmers recommend boron, as in borax or boric acid.
Not only is the element safer, when used properly, but it is more effective in the long term, according to Roy Smith, co-founder of the Hawaii Organic Farmers Association.
"The best strategies for ant control come from understanding the ant's social structure," said Smith, who farms pineapple and taro on Maui.
Old, sick and weak ants are used as taste testers, said Smith. The system serves as a kind of social welfare, as well as providing protection for the colony.
"The colony's main task is to protect the queen," said Smith. "If you try to attack the ants with strong poison, anything that kills the ants within 15 days, you'll kill the sick and the week, but the rest will throw out the poison. You won't get the queen. You're after the queen, if you get the queen you've got the whole colony."
He recommends a 1 percent boron solution mixed with honey, grease or whatever your ants seem to be after. Most commercial boron-based pesticides are 3 percent or higher, said Smith, which is too high for a queen-killing strategy. "You get the testers, but you don't eliminate the colony," he said.
Boron also can be harmful to animals, but unlike Diazinon, which is broadcast over the area to be protected, it is most effectively used in baiting stations. That is, take the boron/food mixture and place it in a housing that is accessible to the ants, but not other critters.
"You can tailor the presentation to match their feeding habits," said Smith.
Diazinon is popular with gardeners partly because ants presage an increase in the populations of sucking insects, like aphids, that damage plants, according to Kimberly Clark, who runs the Just Add Water organic farm in Waimanalo. Ants farm these bugs and harvest the sugars they extract from plants.
"If you deal with the ants, you deal with a lot of stuff," said Clark, who also teaches organic gardening.
A quintessentially organic way to curb an ant colony's insect farming habits is to provide it with an alternate food source, said Smith.
He recommends the Inga bean tree, which produces nectar pods and grows well in Hawaii.
"It produces a large pod that looks kind of like a tamarind," said Smith. The pod's sweet, pulpy interior lends it the colloquial name of ice cream bean. In addition to providing a nonbuggy food source for ants, the tree improves the soil by restoring nitrogen.
Clark recommends planting Neem trees for general pest control. A tea made from the leaves also can be used to disrupt the reproductive cycles of insects, she said.
While treatments aimed at long-term results are the ideal, according to Clark and Smith there are organic contact poisons that deliver immediate results.
Pyrethrin, made from the chrysanthemum flower and the active ingredient in commercial flea killers, will kill ants on contact, but will do nothing eradicate the colony. It can be used to keep bugs out of specific areas.
Diatomaceous earth, a crystal sold at pet and garden shops, is another contact poison. It paralyses the bugs and they eventually die. "It's a slow painful death," said Smith. Diatomaceous earth doesn't seem to affect larger, beneficial insects (like the carnivorous praying mantis) and is not harmful to pets, said Smith.
Clark also encouraged gardeners to maintain organic slug bait in areas where plants are being eaten.
"You may think that you have some sort of insect infestation, when really you have slugs," she said. Copper wire works as a guard if you have some handy. Iron phosphate is effective, but harmful to birds, said Clark. The best defense is probably half empty cans of beer, which the slugs will slime into and die.
But the best line of defense against insects, according to Clark, is keep your plants and soil healthy.
Gardening Calendar in Do It Electric!
Stephanie Kendrick's gardening column runs Fridays in Today.
You can write her at the Star-Bulletin, P.O. Box 3080, Honolulu 96802
or email email@example.com