Cultural Control of Disease


Headache !
Aug 12, 2006
Crabapple trees are so popular in Michigan, and almost all of them look like hell by late August because of apple scab. Leaves are brown by late summer & trees are defoliated by early October. I always let clients know that a good fall clean-up will help by getting rid of the leaves that carry the fungus, but I've never really tracked this advice to see if it's effective ?
Do any of you have experience with using only cultural control, or is it always in conjunction with sprays ?
Also, is dormant oil helpful for apple scab, or just the carefully timed (2-3) fungicide sprays in the spring ?
Coddling Moth is our big thing over here for crabby apples, big program to eradicate it with sterile insect release as it ruins the fruit in the orchards. Crab apples are basically being eradicated around here to control this problem as there are alot of orchards around. Pruning to eliminate fruit on crab apples and picking all of the fruit off and good clean up in the fall are promoted if you have a hope in hell of keeping your tree (they can force people to remove badly infected trees here). I have never sprayed crab apples but have looked after a couple for the last six years and this year was the first year of coddling moth larvae found on the trees, I've been slacking :(
I have only seen scab 2 years in past 16. One big plus about dry weather in ND. It was common in Illinois of course. I am betting that cultural control, outside of possibly planting resistant varieties, is not going to work in your area. If I am wrong, let me know.
Cultural control may help, but for best results Id say spraying would be best in addition to. And instead of cleaning up the downed leaves in the fall, they should be cleaned up all throughout the growing season. Pruning for air flow can help some too.
Ultimatley it comes down to weather conditions, if the weather is cool and damp as the leaves are developing in spring they are easily invaded by the fungus. If the damp weather comes after foliage hardens off chances for less severe scab are good.
And no matter what the conditions or the treatment, some crabaaples are just genetically sucepitable to the fungus and will get it no matter what.

Last year here in MN, was the first year it wasnt so bad, but for at least the 8 years prior condiotns have always been prime for it.

To answer your question- no, I personally have not had good success with ONLY cultural practices to eleviate the fungus. But it certainly cant hurt.
What are "cultural practices?" Are these actions other than pruning, spraying, fertilizing, injecting? Things like you mentioned are collecting and disposing leaves, fruit and other tree debris. Are there other "cultural" things? Changing watering schedule? Mulching?

Copper is a misunderstood (except for the market) tool, and it doesn't have to be only in the scientist's domain.

Even rather than manufactured supplements, burying a coil of .14 gauge (no varnish) along with the rootball helps in amazing ways. Even pennies hold more value as a fungicide than money. I'd call this a cultural adjustment. It's all in how we judge ourselves as civilized or not.

It's been the fundamental componant of fungistatic and cydal controls for centuries, and more recently (since big Ag-business consists with big energy bizzies) is still the compound (raped in many forms) of all the major fungicidal treatments (for both plant and human protocols). It's just presented in differing marketing forms for us subconcious purchasers / the better looking and more expensive the bottle, the more apt we are to buy it.

Again and as always, the pH of the root zone is step ONE in diagnostics, subparted "B" by symptomatic presentations of the plant. If creeping upward, reduce down and add additional micro-elements that have been bound by the higher pH. No need to target the pests, they're just a symptom and like medicine, if you ask a doctor he'll sell you something.

I think as important as any one person having a personally-available medical file on hand (so an assigned physician can properly figure your problems out), we should have soil records for areas of our concern and responsibility - they're changing very fast now yet the news isn't quite ready for us to be ready to accept that. Hating the word Holisitic 'cause industry taught us to, modifying the soil to treat a plant disease isn't no different than infusing saline into our veins to correct dehydration post haste. Other than compost, seeds, plants, manuals and tools - garden supply stores, nurseries, and ag-service centers should sell nothing except the right information and old-fashioned American-made real leather work gloves.

Scarify copper wire, bury it as a you would scions, pour cider or white vinegar suffucient to wet it down 2 inches deep and wait for simplistic reality to work. Or spend $450 a quart for some high-tech noxious toxic shit and hope for the best - just wash your hands and change your clothes before screwing--up some innocent's life.
We poke the wire into the ground, pour a little vinegar over it? How many spots?
I was thinking about Flowering Crabs, and Apple Scab Fungus, so not too big.
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What it takes for any type of treatment is follow-up. That's where I lack.
If I could have the luxury of control-groups, it'd make my own private study a lot more interesting & realistic. I tend to do hit-&-run pruning. When customers call me back, I have a chance to evaluate my own work... but that is the exception.
Your experiance is typical.

Thats why I do not cable anymore. The idea that the cable will be inspected down the road, is a fantasy.