It was with the object of reducing these difficulties to the practical minimum that 

 field experiments were undertaken by this station. The problem was to find a 

 formula of appUcation* in which the water should be reduced to the lowest possible 

 amount, but without serious damage to the germinating seeds. 



The Cowls Farm Experiment, 1919 



This experiment was located on a field so heavily infested with smut that the 

 loss was almost complete during the preceding year. Three formulas were used, 

 1-64-3200, 1-96-3200 and 1-128-3200. The rows were 150 feet long, two untreated 

 rows alternating with each plot of four treated rows and the whole series in triphcate, 

 thus giving a total of 1800 feet of row treated according to each formula. Plots 

 were planted on April 22. The soil was fairly moist when planted; there was only 

 a slight precipitation during the next week, but the month of May was very rainy. 

 No difference between the rows was apparent when they first came up but within a 

 short time the treated rows looked greener and were thicker because of the dying of 

 the smutted plants in the imtreated rows. This dwindling continued throughout 

 the summer as more of the smutted onions died and disappeared. On June 2, the 

 number of onions in measured lengths of the rows was counted. Also the percentage 

 of smut among those standing was determined. From an inspection of these data 

 (Table I) it is apparent that there had been a large shrinkage from smut before that 

 date and that half, at least, of those still standing in the untreated rows were 

 smutted. Smut was not eliminated from the treated rows but it was so reduced in 

 amount that the rows were too thick for the growing of bulbs of good size. During 

 August thrips did serious injury, causing the tops to die prematiurely. The bulbs 

 on the check rows were much larger than on the treated rows because, after most of 

 the seedlings died, they were far apart and had thus opportunity to grow larger. 

 Very few of the diseased onions were still standing at harvest time and most of them 

 were rotted at the base. Only rarely did one attain a diameter of one inch. The 

 number of sound bulbs in each row was counted as they were pulled. After they 

 had dried for a few days, each plot was also weighed separately. The data is sum- 

 marized in Table I (p. 27). The comparative yields of treated and untreated rows 

 are also shown in Fig. 4. The difference between the results secured by any of the 

 three formulas is not large. Any of the three shows a gain of over 250 bags (100 

 lbs. in a bag) per acre. The control secured by the use of any one of the formulas 

 was satisfactory. 



If one prefers to measure the efficiency of the treatment by the gain in pounds, 

 the 1-96 formula was somewhat the best. If, however, he wishes to consider the 

 number of healthy onioLs at harvest time as the basis of comparison, the 1-128 

 formula is somewhat better, t 



♦Formaldehyde (i.e. the 32-40 per cent, solution of the gas in water) cannot be applied in the concen- 

 trated form to the seeds in the row because even a very small quantity prevents the seeds from germinating. 

 It is therefore necessary to dilute it with water. The first question to be answered then is: how much 

 should it be diluted? This is the first variable in the experiments but this variable depends in turn on a 

 second variable viz. the rate at which the diluted solution is to be applied to the row. For example, a 1-50 

 dilution is excellent if a gallon of it is applied to 700 feet of row but disastrous when applied to 200 feet and 

 worthless when applied to 1400 feet. The numerical expression of these two variables is called the "form- 

 ula of application." For all of our experiments it is written in terms of pints of formaldehyde — pints of 

 water — feet of onion row. To illustrate: the formula 1-50-3000 means one pint of formaldehyde is diluted 

 to 50 pints with water and the 50 pints of diluted solution applied to 3000 feet of onion row. Thus the 

 first and second figures express the rate of dilution while the second and third figures express the rate of 

 application of the diluted solution to the row in terms of pints of solution and feet of row. In the literature 

 on onion smut control the rate of application is commonly expressed as so many gallons per acre of onions. 

 This is undesirable because we do not treat acres but rows, i.e.. the amount of solution should be propor- 

 tionate to the number of feet of row and not to the area of the field. The number of feet of row in an acre 

 varies according to the distance between the rows. Different growers plant the rows at different intervals. 

 Even in the restricted area of the Connecticut Valley one may find fields of onions planted at 12, 13, 14 or 

 15 inches and none of them is uncommon. In other sections of the country under different methods of cul- 

 ture other intervals are used. In order that results obtained at one place may be compared with those from 

 another, it is desirable that formulas be expressed according to length of row treated and not acres. It 

 should also be kept in mind that a direct comparison cannot be made between the results of the use of two 

 formulas in which both variables are fluctuating at the same time: One must remain constant while the 

 other is being changed. 



f Methods of calculating the results: The writers have given considerable thought and attention to the 

 question of the most accurate method of calculating and comparing the results obtained by the use of the 

 different formulas of application. The methods which we have tried — most of which are in use by other 

 investigators— are : 



1. By counting the number of smutted seedlings when they are in the cotyledon stage. This method is 



14 



