Birds are Friendly Destroyers of Weeds

Harm done by weeds. Weeds constitute one of the greatest enemies against which the farmer or gardener must contend. During the growing season he must wage a constant warfare against them.

Weeds may be injurious in the following ways: (1) Weeds interfere with the growth of crops by depriv­ing them of plant-food, moisture, and sunlight and thus reduce the yield. (2) Another loss results from the mixture of weed seeds with the seeds of farm crops. It has been estimated that in the State of Minnesota alone the damage due to weed seeds amounts yearly to two and a half million dollars.

(3) Weeds interfere with the harvesting and curing of crops. (4) Some weeds harbor insect pests and fungus diseases, which may injure crops growing near.

(5) Some weeds are poisonous either to man or to live­stock. A recent bulletin published by the Department of Agriculture estimated that weeds cost the Amer­ican farmer three hundred million dollars every year.

The seed period of the' weeds is one of the most vital at which they may be attacked. It is the migration stage during which they are spread from place to place. Many of the troublesome qualities which weeds possess are due indirectly to certain characteristics of the seeds: (1) the enormous num­ber produced by a single plant; (2) their remarkable adaptations for dispersal; and (3) their wonderful vitality.

Productivity of weeds. A single plant of many common weeds like the foxtail and the lamb's-quar­ters may produce 25,000 seeds. It has been esti­mated that a single plant of purslane may produce 100,000 seeds; of pigweed, 300,000; of lamb's-quar­ters, 1,800,000; and of wormseed, 26,000,000. At Ames, Iowa, a square rod of ground in a garden, which had been in potatoes the year before and cul­tivated with a hoe, yielded 187,884 plants of eight common weeds.

Dispersal of weed seeds. The seeds of weeds are well adapted for dispersal. Many are scattered by the wind; some of the tumble-weeds are rolled along on the prairies; some have winglike attachments, like the docks; others have hairlike appendages, like the dandelions. Others have hooks by means of which they may be attached to clothing and fur and . thus be carried long distances.

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