Agriculture Reference
In-Depth Information
Mechanical Cultivation
This method is more effective for annual weeds than perennial weeds. With
aggressive perennial weeds, particularly those that spread by rhizomes, one
or a few passes of a tiller or disk are more likely to increase the weed prob-
lem than to reduce it.
If your soil is deep enough and the weeds are confined to the top 4 inches
of soil, try deep plowing with an inverting plow before adding the soil amend-
ments we discussed earlier in this chapter. The goal is to bury the seeds and
rhizomes so deeply that they cannot resprout. A typical moldboard plow may
not bury the weeds and seeds deeply enough. California fruit specialists re-
commend using a Kverneland rollover plow for this operation. When farm-
ing on shallow soils, be careful not to turn your productive topsoil under and
leave unproductive subsoil on the surface.
Repeatedly tilling or disking bare fallow ground for one or two growing
seasons can also help destroy rhizomes, roots, and tubers from which per-
ennial weeds resprout. Shallow disking or harrowing is less likely to create
a hardpan or damage soil structure than is rototilling. Cultivate the field as
early in spring as you can without causing the soil to compact. As soon as
the field begins to green up, cultivate it again to kill the young sprouts and
seedlings and gradually deplete the food reserves in the underground tis-
sues. To reduce the adverse effects of leaving the soil bare for long periods
of time, you can plant a biofumigant green manure crop in early spring and
till it in before the seeds mature. Keep the soil bare using cultivation during
the summer, and replant the biofumigant crop in fall as a late green manure
crop. Repeat this process for 1 or 2 years.
If you choose to keep your orchard land bare using repeated cultivation
to achieve weed control, follow up with 1 or 2 years of biofumigant and green
manure crops. Use crops that form dense stands that shade out and out-
compete weed seedlings. In warmer areas with prolonged growing seasons,
you should be able to establish and till in at least two green manure crops
in a single growing season. Be sure to till these crops under before they set
