Joined: Mon Sep 25, 2006 9:55 pm
Location: Riverside, Southern California USDA Zone 10a
So. Calif. Low-chill apple report, Spring 2007
Experiences this spring got me wondering if low-chill performance of apples is affected by the chilling needs of the rootstock.
I grafted well-chilled scions on refrigerated Bud-9 rootstock and Bud-9 roots that spent a warm winter in our ground. The ones on the refrigerated rootstock took off but the ones in the ground sprouted a little bit and then dried out. A few weeks later I started getting suckers from the rootstock (we got about 350 chilling hours this year).
Could it be that some apples that are slow to blossom and bud burst in warm climates could have improved performance on a low-chill rootstock? I have read of such rootstocks from Himalayan Crabapples that also have scab and wooly aphid resistance. Information is scanty on this, as most rootstock breeding efforts are directed toward better cold hardiness in northern climates.
Apples are grown extensively in the tropics, often times on local seedling rootstocks. Apparently apples take on a different growth habit in the tropics, acting more like a bush than a tree. The branches are trained horizontally to induce bud burst, and hand-stripping of leaves within three to four weeks after harvest is replacing nasty sprays to get them to blossom. Bagging is also replacing insecticides and disease sprays.
Rome Beauty is popular in Indonesia, a report that I was somewhat skeptical of. But this spring all four of my Rome Beauty trees, whether potted or in the ground, had complete bud burst by Easter and is setting a nice crop. Another surprise was Ribston Pippin, which also blossomed well and set fruit the second year along with Snow, Lady, Chestnut Crab, and Braeburn. Not unexpectedly were the traditional Southern apples Mattamuskeet, Tarbutton, Granny Neighbors, Terry Winter, and Shockley (Cantrell strain).
Fuji has been blossoming earlier every year. Is it possible it is adapting to the climate? When we first planted it, it blossomed in late June, about the time Anna was harvesting. Last year it blossomed in late May, setting a couple of apples. This year it exploded in blossoms the first of April, and is setting a huge crop.
Last year some trees showed classic signs of inadequate chill, such as delayed blossoming and bare wood on the branches near the trunk. Weâ€™ve trained these branches almost horizontal, and will report the results from this, as well as the results of using the center leader, slender spindle, and horizontal espalier training systems.
We are also importing 8 varieties of traditional Southern apples now extinct from cultivation in this country from Tasmania, including Poorhouse, said to be a better keeper than Ben Davis. This is a three year process as AHPIS clears them of viruses, so don't hold your breath.
Kuffel Creek Apple Nursery
Riverside, Southern California
USDA Zone 10a