Control Aik 



matically to determine the most favorable combination. In ordinary farm 

 practice, manufacturers' directions are followed. 



To date, no one has devised a method which is demonstrably better than 

 the one described. There is, for example, no evidence that distributing 

 the fumigant over a plane several inches wide (spraying over the whole 

 width of a flow furrow, for example) is any better than simply ciribbling 

 the fumigant in lines. And most certainly, emulsions, powders, and 

 granules applied to the soil surface are wasteful, since some fumes are 

 lost into the atmosphere. In addition, the great bulk of the chemical 

 is likely to be retained in the upper few inches of the soil whore the 

 fumes are too readily dissipated. Instructions regarding application 

 of sxifficient quantities of water to obtain adequate leaching of the 

 chemicals, and recommendations to working solid forms into the soil must 

 be carefully followed. 



At best, soil fumigants are still expensive and the usual reason for 

 the commercial grower to use them is to increase profits from the 

 projected crop. The profits may come as a result of increased yield, 

 better quality, in savings on some other operation, or from a combina- 

 tion of all three. The tobacco farmer gets more pounds per acre and is 

 content if quality is not appreciably reduced. The sweet potato grower 

 may increase both yield and quality. The carrot grower eliminates culls. 

 The celery grower who fumigates his seedbeds with methyl bromide saves 

 expensive hand weeding. But whatever the advantage, it can be reduced 

 to a dollars and cents basis so that the cost of fumigating an acre ran 

 be balanced against returns due to fumigation. 



It is this comparison which is of interest to the practical farmer, 

 rather than a comparison of nematode control in treated and untreated 

 areas, or one based on general appearance of the field. Thus, the 

 optimum application of soil fumigant is that which produces the greatest 

 cadireturn for each dollar expended for fumigation . Considered from the 

 purely monetary angle, row treatments may be better than solid treatment 

 and a light application better than a heavy one under certain coniiitions. 

 A fact which has become apparent as soil fumigation has progressed is 

 that it is not necessary to kill all of the nematodes to make a ver^ 

 great difference in the crop. In many cases, all that is necessary is 

 to kill enough nematodes so that the plants are not subjected to an 

 overwhelming attack in the early stages of growth when they are most 

 vulnerable. 



It should be recognized that the considerations and techniques may be 

 different for certain special commercial growing enterprises, such as 

 where biennial and perennial plants are concerned and for the home 

 gardener determined to grow good home garden and ornamental plants. 

 The point is, due consideration should be given to the intentit)]i;; and 

 needs of the grower, particiilarly when the cost factor is invlvid. 



In addition to control of nematodes in soil before the crop in ii:nled, 

 there are several other situations where nematocides am or luiclit he 

 used. 



