Date of Award:

5-1954

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Department name when degree awarded

Agronomy

Committee Chair(s)

D. C. Tingey

Committee

D. C. Tingey

Abstract

Dodder (Cuscuta spp.) is a parasitic weed which attacks alfalfa, clovers, lespedeza, and many other species of plants. This pest is especially troublesome when these crops are grown to produce seed.

Control of dodder should increase the financial income of a seed producer in several ways. First, control should make it possible for a producer to raise seed of high quality which will command a better price; second, it should enable the producer to increase yields; and last, it should eliminate much of the cost of harvesting and cleaning his product.

Where dodder is present in seed, the grower loses money because of the reduced quality of the seed. Most states have regulations which make it impossible to certify seed from dodder-infested fields. Thus, if dodder is present, a certified seed producer is forced to sell his seed as uncertified at a lower price. In the south San Joaquin region of California in 1951 (13), 86 per cent of the seed lots were rejected for certification because of dodder. This exemplifies losses occurring in other parts of the West. Some states have seed laws which require a producer to mow the crop for hay before any dodder seed matures, and others prohibit the movement of contaminated seed across state lines. These laws, if enforced, would almost eliminate the seed business from the West under present conditions. In addition, consumers of Western seed are refusing to buy dodder-infested seed; therefore, this pest prevents many growers from finding a ready market for their product.

Dodder greatly reduces alfalfa seed yields and, under extreme conditions, may prevent the production of alfalfa seed entirely. A report by Stitt (25) on dodder control in lespedeza shows that lespedeza seed yields were 212 pounds per acre where dodder was present as compared to 712 pounds per acre where dodder was controlled. This represents an increase in seed yield of 500 pounds per acre just by controlling dodder. Yield reductions such as these mean the difference between profit or loss on a seed crop.

At present, mechanization has almost taken over seed harvesting. Many farmers like to combine seed directly from the stump to save hand labor; however, large patches of dodder often will plug a combine, making it necessary to stop operations and clean the machine. Seed losses also occur where dodder seed must be removed from the seed crop. It was reported by Harvey (13) that in recleaning clover seed to remove dodder, 8 per cent of the clover seed was lost. This loss, added to the cost of cleaning, provides another illustration of the value of dodder control.

Checksum

30df05f22c401e22bb01f6b309e6bf74

Download

Share

COinS

Copyright for this work is retained by the student. If you have any questions regarding the inclusion of this work in the Digital Commons, please email us at .