Chapter 14

Weed Management for Organic Crops

Controlling Weeds by Mowing

Mowing is another option used by organic growers in controlling weeds and in orchards and vineyards. It is a relatively fast operation that causes minimal soil disturbance, although soil compaction may become an issue where mowing is frequent. Mowing weeds or cover crops can be used to produce mulch material for weed suppression in the inter-row or intra-row areas. Growers should consider a program of mowing alternate rows, allowing the uncut rows to provide habitat and food sources for beneficial insects in the orchard or vineyard.

Types of Mowers

There are three basic types of mowers: the sickle-bar, rotary, and the flail (See Figure 14.16). The sickle-bar consists of a cutting bar with attached guards and a knife (sickle) that is driven back and forth in a horizontal direction. Rotary mowers have blades that rotate parallel to the ground, which coarsely chop and cut weeds that are growing on the orchard or vineyard floor. They can be mounted on the front or back of a tractor. Flail mowers have numerous small blades that rotate perpendicular to the soil surface, which cut the weeds into smaller pieces. Flail mowers are often mounted in the rear of the tractor. Mowers are often the preferred method for managing weeds, especially on hillside orchards and vineyards, where growth is very vigorous, and in no-till systems. Flail and rotary mowers with side-delivery chutes can be operated to place the clippings as a mulch within tree/vine rows, helping to move nutrients from the row middles to the tree/vine row and suppress weed growth.

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