Wednesday, July 1, 2020


Sanctuary, as it applies to pest control in the garden, is a strategy to ensure that a large percentage of the pest population remains naive to your pesticides or control methods of choice.

For example, suppose you use the popular pesticide Sevin (Carbaryl) to control Colorado Potato Beetles.

Sevin, when it works, works very, very well. But Colorado Potato Beetles rapidly develop resistance to it.

"Sanctuary" involves deliberately not spraying some heavily infested potato plants when you are spraying your garden.

"WHAT!" you exclaim. "Won't they just lay eggs and you will be faced with a second generation?"

True enough. But it will be a second generation that is naive to Sevin.

It is better to let 95% of the beetles that survive to reproduce to be not-resistant rather than to have 100% of the beetles that survive to reproduce to have some, qualitative resistance to Sevin.

As long as the genes that produce resistance are recessive or incur significant metabolic disadvantages, it is unlikely that most of the beetles will manifest resistance to Sevin.

Obsessive Compulsive Disorder
"Sanctuary" is  very different mind-set than the "Farm as pretty as a calendar cover" goal. It is also different than what Ag Chemical companies promoted until very recently.

They wanted to sell a lot of product. They wanted you to carpet-bomb your crops and farm animals.

But now the thinking is shifting. If you have a herd of cattle, for instance, and only 20% of them have clinical symptoms of worms, then treat the 20% and then cull them when you have a market for them.

There are genetic components to resistance to worms within farm animals. Keep and breed the ones that exhibit resistance. Sell the others.

The ones without symptoms will still have a worm load. They will still drop viable eggs on the pasture. But it is within the bounds of what the dynamic ecosystem can absorb.

The risk of carpet-bombing with an worming medicine is that you will eventually encounter a stressful year when even your animals that are not predisposed to worms get symptoms. It might be the year when it rains every day for two months strait.

If you carpet-bombed the previous fifteen years, then your medicine of choice will not be very effective. You will lose animals. You will lose money.

If you exercised some kind of sanctuary strategy, then your worming medicine of choice will likely work very well.

Potato bugs
Tomorrow I will spray my potato plants. I have a ten year-old bottle of Sevin of dubious potency. I will skip three infested plants per row.

I also have issues with Japanese Beetles in the grapes. Japanese Beetles love grapes. Sanctuary is easier with Japanese Beetles because there are so many wild species they eat that are never sprayed. There is no shortage of naive beetles diluting resistant genes.


  1. Tomorrow I plan on spraying my potatoes if the wind is not too high. The population is much higher than normal and my vacuuming control practice is wearing me out and taking too much time. So back to spraying. I'll try your technique. Thanks.--ken

  2. Don't know how to communicate with you otherwise so I tack it here. We play back gammon with our children. My son, this morning characterized it as a game of chance. I told him partially, the dice are like life. Random things come at you and your strategy for dealing with it is just like the strategy for moving you pieces on the board. There are moves that leave you covered and there are moves that leave you open. The less you leave yourself open the closer you come to winning. You also have to take advantage of opportunities left in front of you.


Readers who are willing to comment make this a better blog. Civil dialog is a valuable thing.