Apricot

(Prunus armeniaca)

Background

Apricot is a fruit crop with a long history of domestication. The center of origin for apricots is considered to be Afghanistan, although secondary centers are uncertain due to wide distribution from extensive, prehistoric cultivation. It is now widely grown in Eastern Europe, India, the Middle East, Asia and Japan. There are no native species in North America. Prunus mandshurica from northern China forms the basis for some older winter hardy cultivars for the Midwest like ‘Scout’. Prunus siberica is the most winter hardy species (-50 degrees F) and is naturally very dwarf, with quite inedible fruits, but useful in breeding.

Apricot is another Prunus species with a short chilling requirement and early bloom period that make it site sensitive and limit its adaptability for commercial production. It is being incidentally observed in the Carandale test plot. Observation has been limited by misidentification and inaccessibility to cold hardy cultivars.

Observations at Carandale Farm

‘Harglow’ was ordered from Raintree Nursery in 2003 as a possible cross pollinator for the Tlor-Tisiran black apricot. Two trees were planted and both looked healthy going into the winter. They leafed out in the spring of 2004 and even had a few blossoms, but the leaves wilted when the weather warmed and one tree died. The other struggled to survive through the summer, but was also dead by the following spring. Symptoms suggest that it was a rootstock hardiness problem.

Dormant 'Sungold'
Dormant ‘Sungold’

One each of ‘Puget Gold’ and ‘Westcot’ were ordered as replacements from Fedco Trees in the spring of 2005. Unfortunately, ‘Westcot’ was out of stock, but the tree labeled ‘Puget Gold’ was planted and adapted well. ‘Westcot’ was not listed in the 2006 catalog. In the spring of 2006 there were a few blossoms on ‘Puget Gold’, but the fruits turned out to be plums — an obvious case of mislabeling.

Carandale started over with ‘Westcot’ because it was said to be a Manitoba, Canada, selection that should be hardy to Zone 4 and “a breakthrough for growers in the Prairie Provinces.” Again, Fedco Trees was out of ‘Westcot’ stock for 2007.

Dormant 'Moongold'
Dormant ‘Moongold’

In 2008, two trees each of ‘Moongold’ and ‘Sungold’ apricots were ordered from Miller Nurseries. Both require pollinators, so they were planted as pairs in two locations. It was obvious from the start that there was a big difference in vigor and adaptability. At one location where the black apricot had just been removed, both cultivars struggled, possible victims of replant disorder. ‘Sungold’ died the first year at that location. In the other location, ‘Moongold’ is a healthy, vigorous tree, but has not yet bloomed. ‘Sungold’ is struggling to survive even at the second location. The comparison is striking as can be seen in photos taken during dormancy in early March 2012.

The experience with apricots has been frustrating. Problems with cultivar selection and availability along with mislabeling and adaptability issues have prevented any meaningful observation regarding their potential as a commercial fruit crop. The first fruit is yet to be harvested, so there has been no observations of fruit quality or susceptibility to insect and disease pressure.

Replicated apricot plantings established at UW-River Falls in 2001 have included ‘Sungold’, ‘Moongold’ and ‘Scout’. Winter hardiness ratings (on a scale of 1-5; 5 being best) are 3, 4 and 5, respectively, for those cultivars. Only two partial crops have been harvested over the last ten years from ‘Scout’ and ‘Moongold’.

Dr. Brian Smith, plant breeder and Extension Specialist at UW-River Falls, is doing research that could make apricots an economically sustainable crop for more growers. Working with seedlings of Manchurian apricot (Prunus mandshurica), he has made two selections that fruit reliably on an every other year basis, with full crops of acceptable quality fruit. Fruit have good flavor, appear to be quite resistant to brown rot and show very little plum curculio damage, without the use of any protectant sprays.

Traditional apricot varieties are not adapted to environmental conditions where winter temperatures are as variable as is common to most of the temperate regions of North America. Like sweet cherries, commercial success will be limited to areas that have a meso-climatic dampening effect on the variability of winter and spring temperatures.

References

Wikipedia entry on Apricot
Royal Horticultural Society information on Apricot

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