9
F
Sof t
f
rui t Day
F
w
ith a packedprogramme, professionally run to time
thanks togreat chairmanship and excellent
communication skills from all the researchers, this
event demonstrated the excellence of research being achieved
on behalf of growers. Plant pathologistswere outnumberedby
entomologists, but this reflects the concern over the economic
impact of failure to control pests likeSpotted
w
ingDrosophila
(S
w
D) on the soft fruit industry. The establishment of integrated
pestmanagement (
i
PM) in crops has becomemore difficult
due to the unintended consequences of having to turn to
chemical control for S
w
D, and several projects are in place to
come upwith ideas tomaintain the effectiveness of natural
enemies andpredators asmethods of control.
SpottedWingDrosophila
The latest research intoS
w
D control was presentedby
MaddieCannon of N
i
AB
e
M
r
. National monitoringover the
last four years highlights the problem. Now spread over the
whole country, but with a concentration in the south-east, and
with significantly higher populations at the start of 2016
compared to 2015, S
w
D numbers in
o
ctober 2016were
higher than ever before going into thewinter. Populations are
now rising in other regions and this is expected to continue in a
similar pattern to that observed in the south-east. Monitoring
confirms that femaleS
w
D are fertile frommid-April tomid-
o
ctober and that this pattern is similar each year. Themystery
of the early arrival of S
w
D in cherry andplumorchardsmay be
due to the nectaries at the bases of their leaves that exude a
sugary solution (extra floral nectar). Both sexes are attracted
and cherry leaves showmuch longer visit times than those to
plum leaves. This informationmay help inform research into the
most attractive baits.
w
ork in the laboratory on determining themost attractive
baits for an ‘attract and kill’ strategy, to increaseS
w
D
pesticide contact and uptake, involves assessing a ‘cocktail’ of
baits.
i
nvestigating the attraction of commercial baits
compared to home-made baits showed that strawberry juice,
molasses andGasser were significantlymore attractive, and
bothmales and femaleswere attracted tobaits.
w
e still need
to establish in field trials that the baits aremore attractive than
fruits in crop. The next stage is to test whether the baitswork
with pesticides and if there are other inclusions that could
make themmore attractive in the field.
i
tmay be possible to
reduce numbers in the earlywinter by attractingbig numbers
of flies inNovember topoisonedbaits. Another idea under
investigation iswhether we can prevent S
w
Ddetecting fruit, or
repel them from fruit toprevent egg-laying using repellent
compounds. So far results are not particularly encouraging, but
there are four compoundswith potential.
e
xploitingS
w
D activity patterns to aid its control is the
subject of aPhD undertaken byBethanShaw. Canwe
enhance the control of S
w
Dby exploiting the daily rhythms of
its behaviour?Bethan has found that egg-laying can be
predictedduringday time (there’s no egg laying at night) and,
T
he
frui
TG
rower
•
JAN
u
A
r
Y 2017
e
M
r
Association/A
h
DBSoft
f
ruit Day 2016
Joanna
w
ood reports
