Fruit tree freeze deaths

Subzero temperatures the second week in November did more damage than just preventing normal leaf drop (see Jan 16 "2014 Gardening Year in Review" post). As normal times for Front Range fruit trees to leaf out have come and gone, realization is dawning among home fruit growers that parts and indeed whole trees are dead. A warm fall did not allow trees to fully enter dormancy leaving them unprepared for the sudden, early subzero temperatures.

The row of sour cherries pictured have only a scattered bud or two alive. These few green buds will likely shrivel when summer heat arrives. Already gummy sap is oozing as a stress sign confusing some that peach tree borer is responsible despite the location higher in the tree than the soil line (no frass present either). See CSU Extension's fact sheet for information about Peach Tree Borer.

Few apple branches
 flowering/leafing on this tree

Not only cherry but in some cases generally hardier plum and apple trees show damage. In addition to fruit trees, damage of landscape shrubs and trees will become noticed more as the season progresses. Notable casualties to date include burning bush and spreading ('Manhattan') euonymus, rose, pyracantha, boxwood, privet, weigela, hibiscus, smoke bush, spiraea and buckthorn.

It's Cherry time

Mature, rarely pruned cherry tree SW Denver

Yields of cherries look reasonable considering the 28 degree F lows we had on May 11 and 12. (See May 12 post on fruit bud damage). Damage at these temperatures was expected to be about 10 percent. Birds also are always a threat and can strip trees of fruit in a few days unless trees are netted.

Tart cherries are hardier than sweet cherries which often winter kill in addition to flower freezing. Sweet cherries are comparable to peaches in this respect.

Recommended tart cherries are 'Montmorency', 'Meteor' and 'Northstar'. If you want to experiment with sweet cherries, try 'Black Tartarian', 'Kansas Sweet' or 'Stella'. Tart cherries are self-fruitful while sweets need a pollinator.

'Montmorency' is the standard tart pie cherry variety that produces a July crop of bright red, firm textured fruit. It is planted in the new (second season this year) "Le Potager" food garden at Denver Botanic Gardens (see photo).

DBG 'Montmorency' cherry

'Meteor' is a very cold-hardy tree growing 12 to 15 feet tall. It develops heavy foliage that can minimize problems with birds. Fruit ripens mid to late July.

'North Star' is a dwarf tree topping out at 10 feet. It sets generally heavy crops of fruit that turn dark red for July harvest.

Note that bush cherries are very hardy and also possibilities. Nanking cherry produces some of the first flowers of spring, can grow to 6 feet and fruit is harvested in July if birds and squirrels don't find it first. Sand cherry is another bush cherry reaching 4 to 5 feet and produces mild-flavored, deep crimson fruit. Both are self-fruitful.

Photo credit: Both Carl Wilson