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Tree Fruit: What are chill hours?

Mississippi's winter chilling information

Deciduous fruits and nuts stop growing in late summer or fall, drop their leaves, and are dormant during the winter, then resume growth in the spring. This relationship between plant and environment is important to the survival of the plant. Growing plants that are nonhardy and incapable of becoming hardy, need dormancy during winter for survival. In areas where winters may fluctuate between cold and mild temperatures, species have developed with long chilling requirements, so they will not begin to grow in midwinter even though it may warm up to growing temperatures for several days.

Endodormancy (rest) is defined as that period when buds are dormant because of internal physiological blocks that prevent growth even under ideal external conditions for growth. Chilling termperatures above freezing terminate endodormancy. Chilling hours are defined as that period of time between 32º F and 45º F. Plants are assigned a certain chilling requirement based on the amount of cold needed to cause 50 percent of the buds to break and flower in the spring. Most blueberries have a chilling requirement of 400-600 hours. Peaches are planted using the chilling requirement as a criteria for variety selection and range from a low of 400 to a high of 1250. Average chilling hours during the winter in Mississippi are: Hattisburg - 400-600; Jackson - 600-800; Mississippi State University - 800-1000; and Holly Springs - 1000-1200.

In 1999, middle to lower Mississippi experienced a low chilling hour accumulation. There is a material (Dormex) that can be sprayed on the commercial plantings that will substitute for about 200 hours. This material is a restricted use pesticide and can damage the plant if used improperly. Dr. John Braswell, Dr. Frank Matta and I have asked for and received, a Mississippi Label for this material.

Dr. Arlie Powell (fruit specialist in Alabama) has performed research and demonstrations with Dormex in Alabama for over 10 years. Information concerning Dormex can be found on their web site, Alabama Winter Chilling

At this time, we feel that we will accumulate sufficient chilling hours, in Mississippi. However, some growers may be interested in discussing the use of Dormex in late Febuary.

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Publications

Publication Number: P3055
Publication Number: IS1608
Publication Number: P0376
Publication Number: IS1445

News

Filed Under: Commercial Fruit and Nuts April 20, 2017

RAYMOND, Miss. -- Growers interested in commercial pecan production are invited to a spring field day May 11 in Raymond.

The event will begin at the Mississippi State University Central Mississippi Research and Extension Center at 1320 Seven Springs Road in Raymond. It is hosted by the Mississippi Pecan Growers Association, MSU Extension Service, and Mississippi Agricultural and Forestry Experiment Station.

Filed Under: Commercial Fruit and Nuts April 13, 2017

STARKVILLE, Miss. -- Growing conditions first helped but then hurt Mississippi strawberries this year as the 2017 harvest season comes to an early conclusion.

Eric Stafne, fruit crops specialist with the Mississippi State University Extension Service, said a mild fall and winter helped the crop mature a little earlier than normal.

Filed Under: Commercial Horticulture, Commercial Fruit and Nuts, Farmers Markets April 7, 2017

WOODVILLE, Miss. -- Farmers market and cottage industry sales are a significant part of the Mississippi food scene, and Mississippi State University Extension Service training is helping entrepreneurs take advantage of these business opportunities.

The MSU Extension Service and Department of Food Science, Nutrition and Health Promotion offers training on acidified canned foods and general food safety at locations across the state. An upcoming workshop will be held April 25 in Woodville, Mississippi, at the J.R. Hamilton Extension Building.

Filed Under: Commercial Horticulture, Commercial Fruit and Nuts, Fruit, Nuts March 23, 2017

CRYSTAL SPRINGS, Miss. -- Producers interested in season extension for specialty crops and commercial strawberry production can learn about these topics during an upcoming field day.

The Season Extension and Commercial Strawberry Production Field Day will be April 4 at the Mississippi State University Truck Crops Branch Experiment Station, located at 2024 Experiment Station Road in Crystal Springs. It begins at 9 a.m. and ends at 4 p.m.

Filed Under: Crops, Commercial Horticulture, Commercial Fruit and Nuts, Beef, Beekeeping, Forestry, Seafood Economics March 3, 2017

BILOXI, Miss. -- Mississippi State University researchers and Extension Service agents heard suggestions from Coastal area agricultural producers and industry leaders about the research and education they need from the university in 2017.

The MSU Coastal Research and Extension Center Producer Advisory Council meeting was held on Feb. 28 in Biloxi. The annual meeting helps the university allocate time and resources to the most important issues facing Mississippi's agricultural producers and related industries.

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