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beet by 176 percent, cabbage by 18 percent, cucumber by 450 percent, and lettuce
by 55 percent. It should be noted, as a basis of comparison with these results,
that damping-off was more severe in soil treated with formaldehyde 2 cc. per
square foot) 30 days before seeding than it was in untreated soil, for the treated
soil had, by that time, become heavily reinfested with soil fungi. Such treatment
with formaldehyde applied to soil before seeding gave good protection for about
5 days, some protection for about 11 days, but practically no protection if seeds
were sowed 11 days or more after soil treatment.

Ammonium Hydroxide and Ammonium Sulfate

Ammonium hydroxide and ammonium sulfate reduced Icsses caused by a root-
rot ot sugar beet if applied to soils having sufficiently high pH values (3); and
ammonium sulfate, with lime, has been successfully used in the protection of
cotton against a root-rot (16).

Ammonium hydroxide was applied to a soil having pH values ot 6.0 or 7.1, the
latter value resulting from the earlier use of hydrated lime. Seeds were sowed
10 days after the application ol ammonium hydroxide, with the results shown in
Tables.



Table 5. — Effects of Ammonium Hydroxide and Soil Reaction on the
Control of Damping-off



Ammonium
Hydroxide'



Relative Number of Plants Which Lived



Percentages
Which Damped-off



Beet Cabbage Cress Cucumber Pepper Beet Cress Cucumber



pH Value of Soil Before Treatment, 6.0

Nsne (check) 100 100 100 100 100

10 cc 227 140 157 120 128

16 cc 268 187 155 225 140

20 cc 240 160 150 214 125

pH Value of Soil Before Treatment, 7.1

None (check) 100 100 100 100 100

10 cc 237 163 182 158 128

16 cc 260 139 156 172 145

20 cc 218 133 158 209 153

'In 1 quart of water per square foot.



40


17


66


8





7




















21


18


18






























The only injury to growth was caused by 20 cc. and that was confined to cress
and cucumber in the scil with a pH value of 7.1. Ammoniuin hydroxide this
used controlled damping-off practically as well and improved stands practically
as much in a soil which, before treatment, had a pH value ol 6.0 as it did in a soil
which had a pH value of 7.1, although control of damping-off by the lightest
application, 10 cc, was slightly less good in the acid soil.

In another experiment (see Table 6), ammonium hydroxide, 12 cc. (in 1 quart
water) per square foot, gave good results in soil with a pH value of 7.1, even when
seeds of beet were sowed immediately after soil treatment ; but for best results
with 16 cc, it was necessary to wait a few days before seeding.



10 MASS. EXPERIMENT STATION BULLETIN 394

Table 6. — Effect of Ammonium Hydroxide, and Interval Between
Soil Treatment and Subsequent Seeding, on Stand of Beet Seedlings

Relative Number of Plants
Time Interval Between Which Lived

Soil Treatment and
Seeding



days. .
3 davs. .
5 days. .
7 days. .
10 days.
12 days.
14 days.



There was a strong odor of ammonia when ammonium su'fate was worked into
a relatively moist soil which had previously been limed. Ammonium suUate, 8,
10, or 12 gm. per square foot, thus applied to soil 24 hours before seeding, gave
good results in soil with an initial pH value of 7.0 but had little or no effect on
damping-off in scil with an initial pH value of 5.9 (see Table 7). Growth of cu-
cumber and cress, but not ot beet and lettuce, was, in this case, somewhat retarded
by 12 gm., not by the lighter applications.

Table 1. — Fesults With Ammonium Sulfate in Soil of the Different

pH Values Named



Ammonium Sulfate



Untreated

Soil

(check)


Ammonium

Hydroxide

12cc.


Ammonium

Hydroxide

16cc.


100


250


87


100


332


134


100


158


127


100


132


167


100


189


228


100


160


224


100


253


306



Beet


Cress


Cucumber

pH pH
7.0 5.9


Lettuce


pH pH
7.0 5.9


pH pH
7.0 5.9


pH pH
7.0 5.9



Relative Number of Plar»ts Which Lived



None Ccherk) 200 100

8 gm. per square foot . . .
10 gm. per square foot . .
12 gm. per square foot. .



None (xhetrk) 29

8 gm. per square foot. .
10 gm. per square foot.
12 gm. per square foot.



200 100


284


100


316


100


185


100


325 138


258


110


300


132


197


100


413 124


267


137


375


147


196


109


229 ...


267




284




190




Percentages


Which Damped-off










29 46


42


72


17


66


18


25


5 11





Zl


I


IS


5


17


2 43





51





22


3


12


.,


















In other experiments, a mi.xture of one part (by weight) of ammonium sulfate
and two parts of hydrated lime was prepared. Both were dry and there was-
practically nc trace of the odor cf ammonia. The mixture was stored in tightly
stoppered glass containers and, after 1 week, worked into soil at such a rate that
each square foot of scil received 10 gm. ammonium sulfate and 20 gm. hydrated
Hme. There was a strong odor of ammonia when this mixture was applied to
slightly moist soil. This treatment, applied immediately before seeding, slightly
retarded the growth ol all species and interfered with the germination of seeds
of cabbage, eggplant, and tomato; but it lessened the severity rf damping-oflT



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 —



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Online LibraryMassachusetts Agricultural Experiment StationBulletin - Massachusetts Agricultural Experiment Station (Volume no.379-398) → online text (page 61 of 77)