Strawberry Crop Rotation Strategies
William Lord, Extension Specialist, Fruits UNH Cooperative Extension
Soil fumigation has never been a viable production practice for the typical New Hampshire strawberry farm due to its relative limited size of just several acres or less. Rather, crop rotations, often limited in scope, have been used to insure maximum potential production in a situation of nearly continuous strawberry production.
The problems that accompany continuous strawberries are well documented - a build-up of specific pests including soil diseases, certain soil insects, and perennial weeds. Other problems include soil compaction from equipment and customer traffic. Breaking the continuous strawberry cycle is a key for managing these problems.
At the minimum, I recommend a 5-year rotation. Of course, proper pre-plant soil preparation before the first strawberry crop is planted is essential. This soil preparation includes installation of soil drainage practices to correct soil drainage deficiencies as well as elimination of perennial weed problems. It also requires correction of soil pH and nutrient deficiencies, and intensive cover cropping to assist in weed and soil insect suppression and organic matter conservation.
The 5-year clock starts ticking the spring the first crop is set out. Year 1 is a grow year, and years 2 and 3 are normal fruiting years - the crop is harvested, renovation follows, and the planting is put-to-bed for the winter. What the planting does in its 3rd fruiting season will determine its future. While some beds are relatively weed-free and healthy at this point in time, and should be carried over one more year, most are suffering from perennial weed invasion and other pests and will need to be renewed.
Renewal starts with eradication of the perennial weeds (including strawberry plants) as soon as harvest is complete. Seed to a summer cover crop immediately. I recommend sudan grass as the first choice, although in shorter season areas, Japanese millet is a better option. In northern areas, it is unlikely either will seed prior to freeze kill in the fall. Once freeze killed, they both make an excellent fall cover, protecting soil from erosion. In southern areas where these grasses may have enough growing season to flower and seed, these grasses should be mowed or plowed down prior to seeding. A fall cover of spring oats could follow. Again, this crop will die in late fall, providing excellent winter cover and an easy to manage spring crop residue.
In year 5 of the rotation, the grower has several options. A traditional cover cropping program can be followed - sudan grass for the summer, followed by spring oats again for the fall - or a cash cover crop option can be pursued. I like sweet corn as a cover for this 5th summer. Sweet corn is an important draw for most roadside stands, it produces a significant amount of organic matter if the stalks are ground up well using equipment such as a flail mower, and incorporated into the soil, and it can be easily followed by spring oats as a fall cover, setting the stage for a new strawberry planting the following spring. Pumpkins are also popular as a cash cover for this non-strawberry year in the cycle.
A 5-year rotation is minimal, at best, and other steps to insure continued productivity are necessary. Correcting soil compaction problems that will develop on many soils from tractor and customer traffic is essential. The use of a chisel plow somewhere in the non-strawberry year will help eliminate compaction problems caused by compaction. You may also want to chisel plow walk aisles as part of the normal post-harvest renovation process if your soil is especially prone to compaction.
Avoid rotation crops that could favor buildup of certain soil pests. You know the rules - do not plant crops such as tomato, potato, pepper, and eggplant (verticillium wilt), legumes (nematodes), perennial grasses (white grubs), etc. I would add strawberry cultivars susceptible to red stele and verticillium wilt to this list, especially for any site with marginal soil drainage. This tight rotation schedule almost mandates that on any site lacking excellent soil drainage, only resistant cultivars be used the second time around.
W. G. Lord Biography