ATLANTI C OAST LINE RA ILRO.A D CO PiANY
21LA Agricultural Department 7 1" 1947
Jacksonville, Florida 4
SE* B O'Kelley H. Sh an A;.
General Agricultural Agent Agricultural Agent
Vol. VI N. o February I 1947
AGRM~LTURAL FIELD NOTES
HO(ESTEAD, FLA. Late blight of tomatoes was unusually severe and de-
btruotive last season not only in Florida but throughout the Eastern United
States and even into Canada. The total national loss to tomato growers in 1946
from the epidemic has been estimated as high as forty million dollars* Late
blight ae- already caused extensive damage to tomatoes in oertais sections of
southern Florida this season, and prospects are favorable for a repitition of an
epidemic of late blS.gb on tomatoes in Florid& should weather continue favorable
for its development and spread and growers fail to employ known effective means
of preventing or checking the disease, according to Dr. Geo. P. Ruehle, Patholo-
gist in Charge of Sub-Tropical Experiment St:ttion here. He says that tomato
growers whose fields are still free of serious infection do not need to suffer
a repitition of the severe losses experienced last year from'late blight, and
that the disease csn be controlled by properly spraying the plr.nt according to
a regular schedule bogun ecrly enough in the season. It is always easier to
prevent blight than it is to chock it once it has bocomo established
He says that field tests conducted at tho Station last season under
extremely severe blight conditions demonstrated that dithano plus zinc sulfate
and hydrated lime applied regularly and thoroughly with a poor sprayer at 5-
to 7 day intervals will control lato blight offoctivoly and will also give good
control of early blight. The formula rjoommondod is dithano (D-14) 2 quErts,
sina sulfate dissolvedd in wctor) 1 pound, hydratod lime 1/2 pound, added in
the order namrod to 100 gallons of wator. The fungioido is compatible with
lead arsonateo, DT, HCH, ottr.blo sulfur, and anganeso sulftto.
Dry Jino-ethylone-bisdithio-c:Irbun&to and phygon plus zinc sulfate
and lime gave good control, but those materials are not-yet genqr3!zy,avaoilablue
It was found that the fixod copper fungicides and bordeaux mixture are genoAi'lly
lose effective against late blight than dithano-zino sulfcto-limo, whon severe
blight conditions prevail, They ara also loss effective for control of early
blight of tomatoes. They will, howovor, control mild casos of lt.o blight or-
will hold it in chock long enough to give an opportunity to apply dithane-zinc
sulfote-lime if the disease boocomos a serious throat. If copper is needed for
nutritional purposes, or 2 copper sprays mny be altornated with dithene"zino
sulfato-lime .crly in the schodulo, provided lato .blight is not seriously throat"
zoning at the time. Bordeaux mixture, if uod, is roeommnndod at tho.4 4 50
formula. Tho fixed coppers, if used as spr.ys, should bo prepared so as to ap-
proximate a 4 4 50 bordeaux mixture in mItqllio copper content.
Whatever the fungicido used, it is r3commondod that from 100 to 125
gallons per acro be applied in the first 2 or 3 applications and that this be
gradually increased to 200 .llons par core for tho last application, Much of
the foliago infection takos placo through the undor surfaces of the lorvos, so
that both loaf surfacoos must be covered at occh application for effective con-
trol. With power mnchinos equipped with drop booms, the use of throo nozzoes
per row properly adjusted will give deoquact coverage whilo the plats aro small'
As the plants rQ~om in siez six pozzlos per row will be rpouirod. Nozzlos
should be readjusted at each application and the spray rigs should be driven
slowly enough to obtain maximum coverage. The operator should be guided by the
visible residue on both loaf'subrfao for t idonee of ndequcoy of coverage.
Spraying should be begun in soodbods as soon as the plants show the
first true loaves and repeated overy 5 to 7 days, depending on the severity of
blight in the area, the weather, ~nd the rapidity with which the plants outgrow
coverage. Spraying should be begun in tho field as soon as the transplants are
well established, A 7-day schedule is adequate until lato blight threatens to
booow epidemic, wheroupon a 5-day sohodula of applications is recommomdod.
Yields of 40 to 100 bushels an c re are being reported to County
Agents by the 400 tfrmore who oooporatod closely with Alabami Extonsion Sorvioe
in carrying out high fortilizor rate demonstrations with hybrid corn. Thoso
;tnaors followed their County Agents' rooommandc.tions on variotios, planting
datos, fortilising, spacing, rad oultit~ting*
TIJFON, GA An open mild winter has rusultod in largo numbers of
volunteer tobacco plants coming up in old tobacco fields, which has created con-
ditions favorable for the dovelopment of blue mold disor.so on tobcooo plant bodso
Workers at the Exporimont Station here are advising frrmors to tcko stops to
control the disease. Thoy report that several spray materials, whon properly
used, will control this plant bed disorso. Furthermore that fermnto is the
ohepeost pray matoriel tested and one of the easiest and safest to uso About
1 I/9 pounds will be ample for spraying a 100-yard bed an entire season.
Suitable fornmte sprCy is prepared by using nine pints of the loose
powder weighing approximately three pounds in 100 gallons of wator. To prepare
the fornato spray placo the powder in a largo fruit jar or similar container
with a small amount of wator and shako or stir until all of it is in suspension.
Then pour into the correct volume of water and spray the plants at tho rate of
3 or more gallons per 100 square yards at o.cch applicr.tion. Bogin with the 3-
gallon rcto on small plants in the 4-lo.f stage, increasing to 5 gallons when
plant leaves roaoh the size of a silver dollar.* ix only enough at one time
for one application and kooeep stirred constantly to prevent settling. If desired
Vatsol-OTO or Vatsol-K mny be used as a wetting agent to got the powder in sus-
pension quickly. One pound of load arsOeIte to each 25 gallons of spray mixture
mny be added to control leaf eating insects.
Begin spraying each year before blue mold appocrs in the plant bed.
If in doubt, begin spraying whon the plants are in the full 4-leaf stage. Con-
tinue regularly twioo a week (Monday and Thursday) until mold develops in the
bed and the plants rocovor, after which applic tions may be discontinued. The
treatment does not prevent all mold infootion but reduces diseo:so damogo to a
minimum It is important to have a heavy coating of spray residue on the loaf
at the time infootion occurs* Therofore, at tho very first sign of the disease
in the plant bod, begin immediately to spr.y at the maximum rmto of 5 gallons
Super 100 yards, rogrdloes of sloe of tho plants. On largo pleats it is safe to
increase the strength of the mixture 25 per cent and spray at the maxiamn rate
during the period when mold is most expected to develop. Plants may be sprayed
through the cover.