F
Scab Cont
r
ol
F
ef
r
uitg
r
owe
r
.co.uk
ThE FrUITGrOWEr •MArCh 2017
T
h
e
r
e is good andbad news fo
r
top f
r
uit g
r
owe
r
s looking
fo
r
p
r
oducts to cont
r
ol scab. C
hr
is Lillyw
h
ite,
hutc
h
inson’s Sout
h
East ho
r
ticultu
r
al Team Leade
r
,
pulled toget
h
e
r
all t
h
e latest advice at t
h
ehutc
h
inson’s
tec
h
nical day t
h
iswinte
r
. G
r
owe
r
swill be awa
r
e t
h
atmany
t
r
ied and testedp
r
oducts a
r
e eit
h
e
r
al
r
eady lost o
r
soon tobe
lost, but new c
h
emist
r
y in t
h
e fo
r
mof t
h
eSDhI g
r
oup of
fungicides, b
r
inging good scab andmildew cont
r
ol,
h
ave
tu
r
ned up just in time. “W
h
ilst we a
r
e losing some p
r
oducts,
we
h
ave suitable alte
r
natives,” saidC
hr
is.
Scab is t
h
emost economically impo
r
tant disease in apples.
Befo
r
e add
r
essingw
h
at sp
r
ay p
r
og
r
amme to employ it is
impo
r
tant to
r
emembe
r
t
h
is is a ubiquitous disease and
infection isweat
h
e
r
-dependent. Site, va
r
iety and g
r
owe
r
p
r
actice a
r
e impo
r
tant inmanaging t
h
e
r
isk of scab. Cultu
r
al
cont
r
ol, suc
h
as sweeping up t
h
e leaves inwinte
r
, will
r
educe
t
h
e inoculum in o
r
c
h
a
r
ds and t
h
is is pa
r
ticula
r
ly impo
r
tant if
r
esistance to c
h
emical t
r
eatments is suspected. T
h
is is
because t
h
e sexual p
h
ase of t
h
e lifecycle occu
r
s in t
h
e
autumnw
h
en in
h
e
r
ited
r
esistance couldbe passed on to t
h
e
next gene
r
ation of scab.
C
h
oosing t
h
e
r
ig
h
t fungicidewill depend on t
h
e timing of t
h
e
application and t
h
e stage of t
h
e infection p
r
ocess. Some
p
r
oductswill only give p
r
otection against spo
r
e ge
r
mination
andmust be appliedbefo
r
e t
h
e infection pe
r
iod
h
as occu
rr
ed.
Ot
h
e
r
swill give va
r
ying levels of kickback o
r
cu
r
ative action.
T
h
e exact c
h
oice of p
r
oduct depends on one’s knowledge of
t
h
e sp
r
ay p
r
og
r
amme up to t
h
at point, combinedwit
h
an
unde
r
standing of t
h
e timing of infection andp
r
evailingweat
h
e
r
conditions.
T
h
e speed of infection is dete
r
minedby tempe
r
atu
r
e andwill
affect t
h
ewindow of activity fo
r
t
h
e diffe
r
ent p
r
oducts. Some
mate
r
ialswo
r
k bette
r
in coole
r
conditions and some
r
equi
r
e
wa
r
me
r
tempe
r
atu
r
es fo
r
best
r
esults. hutc
h
insons’
ag
r
onomists
r
eceive daily updates f
r
om a netwo
r
k of weat
h
e
r
stations t
h
at ope
r
ate t
h
erimp
r
o scab infectionmodel. T
h
is
h
elps t
h
em tomake t
h
emost app
r
op
r
iate
r
ecommendations,
but itmust be st
r
essed t
h
at rimp
r
o is only amodel andwill
only be
r
elevant fo
r
a
r
eas t
h
at
h
ave expe
r
ienced t
h
e same
conditions as
h
ave been
r
eco
r
ded at t
h
eweat
h
e
r
station site.
T
h
erimp
r
o infection
fo
r
ecast gives an
indication of t
h
e timing
and seve
r
ity of infection
pe
r
iods. Even t
h
oug
h
t
h
e
r
e a
r
e p
r
oductswit
h
kickback o
r
cu
r
ative
activity, it is bette
r
to
maintain a
r
obust level of
p
r
otection. T
h
eweat
h
e
r
t
h
at
r
esults in
h
ig
h
scab
r
isk is also not ideal
weat
h
e
r
fo
r
sp
r
aying. As
fa
r
ms
h
ave become
la
r
ge
r
, it can take longe
r
to complete sp
r
ay
r
ounds
and t
h
is canmean t
h
at
t
h
e infection p
r
ocess
h
as
gone too fa
r
by t
h
e time
applications can be
made.
18
W
h
e
r
e a
r
ewewit
h
scab cont
r
ol?
by JoannaWood
