Managing Windbreaks in Vegetables

Gordon Johnson, Extension Vegetable & Fruit Specialist;

Many vegetable growers plant windbreaks between areas where plastic mulch will be laid and vegetables will be transplanted. Windbreaks are often planted between every bed, every 2 or 3 beds, or in drive rows between groups of beds (4-8 beds). Windbreaks protect young transplants from wind damage and blowing sand and can help maintain higher bed temperatures by reducing heat losses from cold winds blowing over beds.

Most commonly rye is used because it is early and is tall compared to other small grains such as wheat or barley. There are several considerations when managing these rye windbreaks. In most cases the rye should be killed with a herbicide, most commonly paraquat, after it has reached full height. This is when the seed head has emerged. Consideration should be given to reduce the chance of seed formation which can become a weed issue in following crops (especially fall planted wheat or barley). When rye produces seed heads, and those seed heads begin to flower (pollen bearing anthers emerge from the seed head) and pollinate, there is about a 7-10 day period before viable seed is formed (seed is set). Burndown should occur before seed set.

If the field is to be followed with cover crop where there is no concern about the rye germinating in the field, then it can be allowed to go to maturity (normal between bed herbicide applications with shielded sprayers may still kill the rye before it reaches full maturity).

One issue with windbreaks is the movement of mites and insects out of the rye and onto the crop after it dies from burndown with a herbicide. Growers should be aware of this issue and plan for control measures during this burndown period if crops have already been planted. If windbreaks are allowed to mature naturally, this rapid outmovement of pests may be reduced initially but may be extended over a longer period.

For very early transplanted vegetables (April-early May) where rye windbreaks are between every 1-3 beds, the rye often is still elongating and may not have produce a seed head. In this situation, vegetables are transplanted before the rye is killed. The rye is managed with row middle herbicide treatments scheduled before vines start to run off of the plastic for vining crops such as watermelon or before staking for upright crops such as tomatoes. A shielded row middle sprayer is used and paraquat is added along with residual herbicide treatments.

For vegetables to be planted after rye has reached full height (May plantings), then a broadcast burndown with paraquat applied over plastic beds and windbreaks is often used. Transplating is delayed until a rain or irrigation has washed off the plastic. Do not use glyphosate for this type of burndown over plastic due the the potential for residuals washing into planting holes, affecting transplants

Where windbreaks are only in drive rows, then they should be killed before seed has set.

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