Crown Gall - Methods of Control

All:

I am in the early stages of establishing a 12 acre high density orchard on the family farm. The first 5.5 acres is cleared, fenced (8' deer fence), and partial planted.

So far I have the following:
- 2,000 sleeping eye trees, planted in permanent rows - 3'x 12' spacing (G11)
- 2,000 2nd yr. bud chipped/sleeping eye liners (Bud 9)
- 2,000 2nd yr. mother plant stool bed (Bud 9) - hoping for 6,000 rootstocks to plant as liners next year to graft
- 1,500 1st year liners (G11,G41,Bud 9)
- 425 2nd leaf grafted trees

After planting the 2,000 sleeping eye trees (which were grafted by White Oak Nursery), I realized that something was significantly wrong with the 2,000 trees I bud chipped.

I have a pervasive crown gall problem that is affecting all trees that have been in the orchard for more than a year. This is likely due to a combination of things: mechanical cultivation of rootstock/liners, trimmed roots at planting/general root trauma, infected soil (was partial pasture/woodlot a year before).



Does anyone have any suggestions on management of crown gall?

Thank you very much.

Best,

Arne Andersen - Broadwater Cidery
[broadwatercidery.com]



Edited 1 time(s). Last edit at 05/24/2016 08:39PM by Arne Andersen.

Your diagnosis is absolutely correct, Arne, and a bummer without question. My only thought is to hope soil biology can undo what Agrobacterium tumefaciens unchecked has with this sort of jumpstart.

Two words: Mycorrhizal fungi. Inoculate these root systems with a range of endo species. BioOrganics is located not too north of you, and I'd get enough of the micronized inoculum to do every square foot of your considerable nursery. Apply as a soil drench. And if you reply that you dipped roots at planting . . . just do it again. The reason you have a biological problem of this magnitude is that enough good guys are no longer present due to excessive soil turning. One month later follow with Trichoderma if you want yet additional fungal pathogen protection. Beneficial bacteria are part of the soil food web plan too . . . whether you deliver such with compost tea of purchase an inoculum product like Root Pro from Lancaster Ag or similar. Only biology can solve a biologically-induced problem.

Lost Nation Orchard
Zone 4b in New Hampshire

Michael:

Thank you very much for your helpful and quick response. I will work on implementing your suggestions over the next couple weeks.

For the chip budded trees, such as the image above, what is the long term prognosis? Is it worth the time to nurse these 2,000 chip budded trees and manage the 2,000 mother plant stool bed? I am assuming the stool bed is a write off because of the high likelihood of propagating crown gall infected trees.

Best,

Arne



Edited 1 time(s). Last edit at 05/24/2016 09:14PM by Arne Andersen.

Someone with nursery recovery experience needs to chime in here. The big question is crown gall systemic in apple? . . . and I suspect the answer might be yes based on what I see in a quick internet look. See this article on crown gall on the American Phytopathology Society website. Robust biology along with cover cropping a questionable nursery site beforehand is intended to preempt the bacterium that causes this disease. Can endophytic fungi in particular undo a gall? DNA transfer from bacterium to plant cell makes prospects for infected plants slim to none.

Your stool bed is likley toast, Arne, but on the other hand it seems worth a shot. Boosting biology is not that expensive, especially compared to the investment you've already made. Just as importantly, you'll be preventing the spread of bacterial reach into tree areas currently showing no sign of crown gall. Even if you pull infected trees, Agrobacterium tumefaciens will still be present in this soil. Don't replant here until you cover crop with cereal grains over two successive summers.

Lost Nation Orchard
Zone 4b in New Hampshire

I will add that the bacterium supposedly needs to enter through damage. When we have seen it, it has been in conjunction with root knot nematodes (cut open the gall to see if this is what you have, they will be in there. In our nursery, we till in neem cake, and often plant marigold to keep these creatures at bay. Any mechanical damage can cause the disease as well.

Since neem cake is a good soil ammendment, it is worth a try to reduce damage. It may have come in on trees, but if the gall was not apparent, it is likely that it was in your soil Arne, or at least possible. Heavy handed folk like large commercial nurseries and orchards often fumigate the soil first.

Walden Heights Nursery & Orchard
Zone 3 in Vermont