CONTROL OF DAM PING-OFF SJ 



and Improved the stand of beet, 52 f)ercent; of cress, 70 percent; and of cucurrlB^f^ 

 175 percent. 



In another case, lime and ammonium sulfate were similarly applied to-soi4- 

 together and seeds were not sowed until 24 hours later Here again, growth of all 

 species was somewhat retarded, but all damping-ofT was prevented and the num- 

 ber of plants which lived was increased as follows; beet by 42 percent, cabbageJiy. 

 29 percent, cress by 45 percent, cucumber by 34 percent, and lettuce by 100 

 percent 



In still another case, seeds were not sowed until 2 and 5 days after soil'Wks 

 treated. Even then, growth of all species was a little retarded in soil into wHIch 

 ammonium sulfate (10 gm.) and lime (20 gm.), together, had been well woirfced, 

 but damping-off was well controlled and the number of plants which livec^^vj^as 

 considerably increased (seeTable 8). For complete safety it is evidently neces- 

 sary to wait more than 5 days after such treatment of soil before seeding. 



Table 8,— Results with Ammonium Sulfate and Hydrated Lime Applied 

 Together to Soil, Two and Five Days Before Seeding 



Interval Relative Number of Percentages Which 



Between Plants Which Lived Damped-pffjV] 



Treatment Treatment 



and 

 Seeding 

 (Days) 



and iio'^l 



Seeding Beet Cress Cucumber Beet Cress Cucumber 



No treatment (check) 100 100 100 25 20 54 



Lime only 125 140 166 6 4 ""'^9 



Ammonium sulfate and lime 2 342 177 257 '^'^^ 



Ammonium sulfate and lime 5 200 ... 286 ., G — 



biupiJ' 



Formaldehvde 



r 'in n,,i! 



Formaldehyde has long been used as a soil dislnfestant but much is stiilbteihg 

 learned about better, more convenient, or more economical ways to use it'in <iOrii 

 trolling damping-off. Examples are the formaldehyde dust method (l,'20)f'4'ri(l 

 the use of relatively light applications before seeding (10, 11). Neither^aff>tltfe"fe'e 

 methods Is, however, wholly safe in the confined air and sometimes cold''^€?lt of 

 sash-covered frames, and both methods make use of more formaldehyde thaiFi':!^ 

 really needed for the control of damping-ofT. Using 0.75 or 0.8 quart of the sblll'- 

 ticn per square foot of soil, Haensler (12) controlled damping-off of beet'wit'h 

 3.5 cc. fcrmaldehyde per square foot; and Ogilvie et al. (17) were able toiiltlprove 

 the emeigence of pea seedlings by 3.75 cc. to 1.25 cc. formaldehyde per* gqikat^e 

 foot. • '[f' "-fifl' 



Formaldehyde, 2 cc. per square foot, gave good results with pea wheb'tl^^^ as 

 described in Table 2. Onion smut has long been controlled by dripping forWiaWt- 

 hyde into the drills with the seeds (19), and It has been similarly and suoid^fuUy 

 used with pea (13) and with spinach (18). Formaldehyde solutions (1 gall^fi to 

 30 feet of row) and formaldehyde dust were applied in the rows after seed* df'p^ 

 were sowed in the field but before they were covered. There was no injury byafty 

 tieatment and theie was an improvement of about 40 percent In stands' floUoA^Itig 

 treatment with a 1:400 solution (see Table 9). That was true also of 'f drJftalde- 

 hyde dust but seed treatments gave even better results. rijiv/ jij.-- 



In the experiments the results of which are summarized In Table lOj^^iekmoM^ 

 hyde 1.25 to 3.8 cc. (In 0.8 quart water) per square foot was applied 'C^Jsoiiisj- 

 mediately after seeding. "i 'J^iv/ od 



