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University of California Cooperative Extension Ventura County
669 County Square Drive, Suite 100
Ventura, CA 93003
Phone: 805.645.1451
Fax: 805.645.1474
Office Hours:
Monday - Friday from 9 a.m. to 4 p.m.
The office will be closed for the following holidays:
November 28-29 - Thanksgiving Holiday
December 24-25 - Christmas Holiday
December 31 - January 1 - New Year Holiday
Nectarine Problems
Problems may include skin cracking, split pits, and skin russeting. The last one is the easiest, so I will start there. Russeting of nectarine fruit is usually caused by the feeding activity of thrips. Thrips are a tiny insect, about the size of the dot above this “i,” that often feed in flowers during bloom. This feeding activity scars the tiny fruit in the blossom. As the fruit grows, the scarred tissues expand to produce the russeted areas on the mature fruit. In the home garden control of thrips is not recommended. The consumption of scarred fruit is not harmful, and the fruit can be peeled if the scarring is objectionable. Severely scarred fruit may be deformed. If this happens often, a spray of insecticidal soap may be warranted. Spray in the late evening or at night when there is no bee activity.
Fruit with split pits often occurs in early maturing varieties of fruit (peaches and nectarines harvested in May/June). The splitting of the pit is caused by rapid growth of the fruit and by excessive watering or watering irregularly (a good irrigation after a dry cycle). To reduce split pits, do not fertilize peaches or nectarines after bloom, and keep the trees evenly watered or even reduce watering slightly after fruit reaches an inch to an inch and a half size.
Skin splitting can have a number of causes and may or may not be related to russeting and pit splitting. Skin splitting may occur when the fruit gets wet from dew, rain or fog drizzle. Maturing fruit can absorb moisture directly through the skin, and the fruit may expand faster than the skin can stretch to accommodate this expansion. The result, the skin and flesh crack. If the skin is russeted (scarred), the cracking may be accentuated. Many of you have heard about the spring cherry crop being damaged by rain (example – the May rains in 2003 caused serious damage and resulted in high cherry prices as much of the fruit split and could not be marketed).
Irregular irrigation, as mentioned above under split pits, can also cause skin cracking.
Too much fertilizer or fertilizer applied too late is another cause. High levels of nitrogen or applications after bloom can stimulate excessive, vigorous growth at the wrong time. For fruit trees apply fertilizer twice a year. Once in the fall (Sept – Oct) just before dormancy, and again in spring as the trees become active, and before the end of bloom.
Cool weather followed by a hot spell can cause cracking. The heat may cause a growth spurt, which the fruit cannot rapidly accommodate.
The general nutrition of the tree may be a factor. Deficiencies of calcium, magnesium or boron can cause skin splitting. These three minerals have important functions in the building of cell tissues. Deficiencies cause weak or inadequate cell formation, and cracking of tissues can result as the fruit expands.
Aphid feeding and the resultant deposition of honeydew on fruit may cause skin cracks. And finally, some fruit varieties just tend to develop split pits and fruit cracks. In a conversation with the manager of a large production nursery, I was informed that some potentially good commercial varieties of fruit trees have been and are eliminated from the market because they tend to develop split pits and/or fruit cracks. Sometimes this tendency is not discovered until the trees are several years old. The only way to correct this tendency is to graft the tree over to another variety or make it into a pile of firewood.