Ask Chris
by CHRIS WINSLOW

‘Chilling Hour’ might sound more like the name of a hip-hop radio show… but in our world of orchards and fruit tree gardening, the meaning is quite different.

Stone fruit trees such as peaches, nectarines, plums and cherries, develop their flowering and vegetative buds in the summer. They go dormant in the fall, as cooler temperatures and shorter days arrive.

Fruit trees will remain dormant until they have acquired the proper number of ‘chilling hours’ (temperatures at 45 degrees and lower). When they reach their chilling hour demand and the weather begins to warm, the fruit trees will break dormancy and begin to flower, leaf out and set fruit.

In the Rio Grande valley (stone fruit chilling zones 6 and 7), where the winters are mild, it is best to pick fruit trees with chilling hour demands of 150 to 300 hours. In north Texas (zones 1 and 2), where winters are longer and more severe, fruit trees with high chilling hour requirements (above 800 hours), would be the best choice.

For our area, a fruit tree with chilling hour requirements in the 500 to 750 hour range is ideal. Low chilling hour trees such as tropiberta and early grande, both peaches, might bloom early and be caught in a mid-to-late winter freeze, lessening its fruit set.

Here are a few favorites for our central Texas area (zones 4 and 5):

Plums
Generally plant at least two varieties to increase pollination and fruit set. The smaller fruit varieties also do the best. Some of the tried and true are bruce, methly, allred, burgundy, and Santa Rosa.

Peaches
Most peaches are self-fruitful, so only one is needed if you have a small area. Some of the best varieties for our area are junegold, belle of Georgia (white fleshed), loring, harvester, and la feliciana.

One later blooming variety that is worth mentioning is elberta. This 750 to 800 hour August peach is a consistent producer and almost never gets caught in a late freeze.

Cherries
Probably the only sweet cherry that has a chance for our area is Stella. Stella is a large, black, sweet cherry that is self-fertile, and has a chilling hour requirement of 750 hours. The problem with growing cherries is the birds like them more than people do (hard to imagine). These trees need to be netted if there is any hope of harvesting fruit.

I’ve started a backyard peach tree orchard and would like to stay organic in my insect sprays. Any suggestions? M. Behr, Manchaca

The best time to spray for white and San Jose scale on fruit trees is when they are still dormant. A great organic spray is All Seasons Oil, which coats the branches with a fine oil that suffocates the scale pests.

Once the peach tree has leafed out, it can be sprayed with All Seasons Oil again for green peach aphids that may begin eating the new growth. Neem oil and Pyrethrum sprays can safely be used also. For worms, the best strategy is to spray with B.T. Baccilus thurengensis that can be bought as thuricide in a liquid or as Dipel in a powder form. Both organically target that pesky caterpillar larva.

Happy gardening everyone!

Ask Chris Winslow. It’s About Thyme: 11726 Manchaca Road, Austin, TX 78748 iathyme@yahoo.com.