Posts Tagged ‘18:sn1’
January 25, 2010
Due to the wet fall in 2009, many vegetable growers on Delmarva were not able to plant small grain windbreaks such as winter rye in fields slated for watermelons, cantaloupes, and other vegetable crops in spring of 2010.
Windbreaks most commonly are planted between groups of 3 or more beds to reduce wind damage and sandblasting on young crops. Some growers have windbreaks between every bed to help trap heat and provide additional protection on early transplanted crops. Winter rye is the most common crop that is planted for windbreaks. It is cold hardy, greens up early, and can reach a height of over 4 feet by late-April making it a good windbreak. Winter wheat and barley have also been used but are later heading or are shorter. Small grains are planted from late-September through early-November. October plantings provide the best combination of tillering and winter cover without excessive fall growth.
In 2009, we had one of the wettest fall periods on record and many windbreaks were not planted. Therefore, information on late winter or early spring planted alternatives is needed. The following are questions and answers regarding late-winter or early-spring planted windbreaks (February-March) to help protect spring planted vegetable crops.
1) Can winter rye, wheat, or barley still be planted in late-winter or early-spring as a windbreak?
Yes, but there is a risk that it will not vernalize and produce stems and heads (may remain vegetative or short).
Winter-planted small grains such as winter rye and wheat will not produce stems and seed heads until after they have been exposed to cold temperatures. This exposure to cold temperatures, resulting in physiological changes in the plant, is called vernalization. The degree of vernalization required can vary by variety. Contrary to popular belief, the best vernalization temperatures are in the 40-50° F range, not at colder temperatures. For vernalization to occur, plants have to be biologically active (cool but above freezing). Those plants that need vernalization require an additional environmental cue, change in day length, to ensure that flowering (heading) occurs in spring. The environmental cues of vernalization and day length change act together to promote spring flowering. Four to six weeks of 40-50°F temperatures are required for vernalization.
Past experience in Delaware has shown that winter wheat planted in late February or very early March will vernalize and be able to produce stems and heads. Winter rye should also follow that pattern. It is critical to plant by March 1 to have the best chance of producing stems and not remain vegetative. For these winter plantings, up your seeding rate to 150 pounds per acre. Rye planted in February will be several weeks later to head and still may not provide full windbreak protection to April plantings. Winter wheat, particularly southern bred varieties, may be more successful, especially moving into early March.
2) Are there other alternatives for March planted windbreaks?
Yes, spring oats, annual ryegrass and tall mustards are alternatives.
As you go further into March, the chance of success with winter rye or wheat is reduced (it may remain vegetative with limited height). The following is more information on alternatives to consider:
Spring oats, planted as early as possible, is probably the best option for March plantings. Use a high seeding rate (120 pounds per acre or more). Oats will provide good ground cover and will head in late spring. It will start to elongate in mid-May. While still not an answer as a full windbreak for early plantings it will reduce sandblasting and provide protection for later plantings. Height will be over 3’ at heading
Annual ryegrass will also produce significant growth from a March planting and provide soil cover. Plant seeds at a rate of 30 pounds per acre. Annual ryegrass can get as high as 3’ when producing seed heads but provides less of a windbreak. One concern is with annual ryegrass is that if it goes to seed it has the potential to become a weed problem in the future.
There are several tall mustard varieties that merit considerations as windbreaks from March plantings. These are “Idagold” mustard and “Pacific Gold” mustard. As these mustards produce a flower stalk, they can reach a height of over 4’. They are often used as biofumigant cover crops. “Idagold” will reach full height and flower 55 days after planting and could possibly provide an April windbreak. “Pacific Gold” also flowers at 55 days after planting and can also be over 4’ in height. Plant at 10 pounds per acre.
Mixtures containing 2 or more of the crops mentioned above (spring oats, annual ryegrass, tall mustards) may be more desirable as a late winter or early spring planted windbreak. Reduce seeding rates of each component by 1/3 in mixtures.
The University of Delaware Vegetable Extension Program will be doing research on windbreak alternatives for late-winter or early-spring planting in 2010. We are seeking on-farm cooperators. If you are interested, contact information is given below.
Gordon C. Johnson
Extension Vegetable and Fruit Specialist,
University of Delaware, Carvel Research and Education Center
16483 County Seat Highway, Georgetown, DE 19947
General Phone: (302) 856-7303, Direct Phone: (302) 856-2585 x 590, Cell Phone: (302) 545-2397, Fax: (302) 856-1845