Brassica Insects & Diseases; Gardening Guidebook for Hampshire County, Massachusetts www.scribd.com/doc/239851313 ~ University of Massachusetts, New England Vegetable and Fruit Conference~ For more information, Please see websites below: ` Organic Edible Schoolyards & Gardening with Children = http://scribd.com/doc/239851214 ~ ` Double Food Production from your School Garden with Organic Tech = http://scribd.com/doc/239851079 ~ ` Free School Gardening Art Posters = http://scribd.com/doc/239851159 ~ ` Increase Food Production with Companion Planting in your School Garden = http://scribd.com/doc/239851159 ~ ` Healthy Foods Dramatically Improves Student Academic Success = http://scribd.com/doc/239851348 ~ ` City Chickens for your Organic School Garden = http://scribd.com/doc/239850440 ~ ` Huerto Ecológico, Tecnologías Sostenibles, Agricultura Organica http://scribd.com/doc/239850233 ` Simple Square Foot Gardening for Schools - Teacher Guide = http://scribd.com/doc/239851110

1. Brassica insects and diseases
Ruth Hazzard
New England Vegetable and Fruit
Conference 2013

2. Brassicas – a diverse crop group
Brassica oleraceaeBrassica rapa
Brassica napa
Brassica juncea
Bok Choy.
Turnip
Kale,
“head
& stem”
Mustard
Red Russian
Kale, Rutabaga
Raphanus sativus, radish
Eruca sativa, arugula

3. Chronological order, more or less
Focus on farm-wide strategies, troublesome pests or
‘something new’
Insects
• Flea beetle
• Cabbage root maggot
• Imported cabbageworm
• Diamondback moth
• Cross-striped cabbageworm
• Swede midge
• Cabbage looper
• Onion thrips
• Cabbage aphid
Diseases
Black rot of Brassicas
Alternaria leaf spot
Downy mildew of Brassicas
Club root

4. Crop rotation goals: avoid building up pest & disease
1. 3 years out of Brassicas
• Is the proportion of cropped
acreage in Brassicas too
high?
• Are fields separated?
• Is crop residue tilled?
2. Separate fall and spring crops
What moves in-season?
flea beetle
cabbage root maggot
thrips
Alternaria
black rot
caterpillars
Swede midge
ADD OVERVIEW OF FARM FIELDS

5. Crop rotation goals:
reduce, escape insects & diseases
Overwintering
locations for
disease: crop
residue in or on
soil, weeds

6. Crop rotation goals:
reduce, escape insects & diseases
Overwintering
locations for
insects: field
edges, crop
residue,
alternate hosts
Overwintering
locations for
disease: crop
residue in or on
soil, weeds

7. Crop rotation goals:
reduce, escape insects & diseases
Overwintering
locations for
insects: field
edges, crop
residue,
alternate hosts
Overwintering
locations for
disease: crop
residue in or on
soil, weeds
Spring?
Fall?
Next Spring?

8. General Cultural Practices
Crop rotation
Incorporate crop residue
Adequate crop spacing
Drip Irrigation
Adequate nutrition
Scout under leaves

9. Pre-plant Prevention: Clean Seed
Healthy Seed
• Seedborne diseases:
– Alternaria (fungal)
– Black Rot (bacteria)
– Downy mildew
• Possible sources:
– saved seed
– purchased seed
Hot Water Seed Treatment
• 15-30 minutes
• 122 F
Needed: screen/coffee filters
accurate thermometer
hot water bath
http://vegetablemdonline.ppath.cornell.edu/N
ewsArticles/HotWaterSeedTreatment.html

10. Cruciferous Weeds Are
Everywhere!
• Four-petaled flower (white or yellow)
• Narrow seed pot, round seeds
• Rosette vegetative
• Tall upright stem reproductive
alyssum hoary Berteroa incana
bittercress Cardamine hirsuta
bittercress cuckoo Cardamine
pratensis
cress mouse-ear Arabidopsis
thaliana
damesrocket Hesperis matronalis
fieldcress prostrate Rorippa x
prostrata
mustard garlic Alliaria petiolata
mustard hedge Sisymbrium
officinale
mustard tower Arabis glabra
mustard wallflower Erysimum
cheiranthoides
mustard wild Brassica kaber
pennycress field Thlaspi arvense
pepperweed field Lepidium
campestre
pepperweed Virginia Lepidium
virginicum
radish wild Raphanus raphanistrum
rocket yellow Barbarea vulgaris
shepherd's-purse Capsella bursa-
pastoris
whitlow grass spring Draba verna
yellowcress marsh
For ID see: UMass Extension Weed
Herbarium – mustard family

11. Regular scouting -- You and the Crew!
• Scout weekly, alone or with the crew
• Notice things! early feeding damage,
tiny disease lesions
• Respond when its not too late!

12. Flea beetles
• Overwinter in field edges
• Find spring crops quickly and
early
• Preference for B rapa, B juncea,
arugula

13. ADULT
Underground, near
plant roots
EGG
S
LARVA
PUPA
Above
ground, on
foliage
Flea beetle life cycle
•Overwinter as adult
•Lay eggs - May
•New adults emerge
midsummer
2nd generation in fall
Peak adult numbers:
1. May-June
2. Late July – early
August

14. Flea beetle Management Strategies
1. Escape them: crop rotation between and
during the season
2. Starve them: no spring Brassicas
3. Kill them: till immediately after harvest, use
insecticides
4. Exclude them: row cover
5. Use trap crops, spray those more often

15. Insecticides for flea beetle
Synthetic
Pyrethroids: 3A
• beta-cyfluthrin (Baythroid* XL)
• bifenthrin (Brigade* 2EC)
• cypermethrin (Ammo* 2.5EC)
• lambda-cyhalothrin (Warrior* II)
• permethrin (Pounce* 25WP)
• esfenvalerate (Asana* XL)
• gamma-cyhalothrin (Proaxis*)
• zeta-cypermethrin (Mustang*)
Carbamates (1A)
• carbaryl (Sevin XLR Plus)
Neonicotinoids: (4A)
Foliar applied:
• dinotefuran (Venom)
• imidacloprid (Provado 1.6F) 7 dh
• thiamethoxam (Actara): 0 to 7 dh
Soil applied: thiamethoxam (Platinum): 30 dh/
in-furrow, banded, drench, or drip; Also seed trt.
Diamide: Coragen
Organic (OMRI listed)
• kaolin (Surround WPOG): use
on transplants, seedlings and young
plants.
• pyrethrin (PyGanic EC5.0OG)
• spinosad (EntrustOG)
• azadiractin (Neemix 4.5)

16. Flea beetle numbers on sticky card traps
2009 UMass Trial on Eggplant
0
0.1
0.2
0.3
0.4
0.5
0.6
no entrust entrust
AverageFleaBeetleCardCountper
Plant
0
0.1
0.2
0.3
0.4
0.5
0.6
no pyganic pyganic
AverageFleaBeetleCardCountper
Plant
0
0.1
0.2
0.3
0.4
0.5
0.6
no kaolin kaolin
AverageFleaBeetleCardCountper
Plant
Entrust, kaolin &
pyganic all
significantly reduced
numbers

17. Flea beetle defoliation on eggplant
2009 UMass Trial on Eggplant
0
0.05
0.1
0.15
0.2
0.25
no entrust entrust
AverageFleaBeetleHerbivoryper
Plant
0
0.05
0.1
0.15
0.2
0.25
no pyganic pyganic
AverageFleaBeetleHerbivoryper
Plant
0
0.05
0.1
0.15
0.2
0.25
0.3
no kaolin kaolin
AverageFleaBeetleHerbivoryper
Plant
Only kaolin had significantly less
feeding damage
Mixtures seem to have an additive
effect

18. We have seen growers use with
success in eggplant:
--Surround alone
--Surround mixed with
Entrust
Row cover also works
great for early season
control!

19. Trap cropping for flea beetle
• Keep it simple
• B rapa, B juncea/mix
– Komatsuna, mustard
– cheap seed
• Borders OR In-field strips
• Main crop: less preferred
– B oleracea, B. napa.
• Scout weekly
• Spray --‘Concentrate &
kill’

20. Full Bloom Farm trap crop study, 2013
bok choy
kale 2
lacinato 2
red russian 2
border mix
kale
lacinato
red russian
border mix
road
last year's brassicas
+ successions of bok choy

21. Full Bloom Farm trap crop study, 2013
• Trap crops:
• Brassica rapa, B. juncea border mix DS
• ‘Sink’ crop (bok choy, napa) (2-4 A)
• Main crop: kale, collard, lacinato, red
Russian (8 A)
• Thresholds: 1 to 2/plant, 10-25%
damage – call for sprays
• Products: Pyganic 16 oz, Entrust 2 oz
– Nufilm
• Results (FB sprays) : 7 sprays on bok
choy, 1 spray on kales (June1 to Aug1)
• Product strategy: Pyganic for knockdown
(rain coming), Entrust for residual, mix if
pressure is high
bok choy
kale 2
lacinato 2
red russian 2
border mix
kale
lacinato
red russian
border mix
road
last year's brassicas
+ successions of bok choy

22. Imported
cabbageworm and
diamondback moth
• Multiple generations
• Scout under leaves, use threshold
(35-50% early, 15-20% at heading,
for leafy greens)
• Use selective insecticides to protect
natural enemies
active
and
wiggly !
Fuzzy &
sluggish!
DAY
NIGHT

23. Cotesia rubecula, Braconid wasp
parasite of imported cabbageworm
• Released 1988 by Roy Van Driesche in MA
• 2011 survey: spread throughout Northeast
and Central US, high levels of parasitism
• Attacks second instars
• Kills caterpillars before feeding damage
• Look for cocoons
White larva inside
ICW caterpillar

24. Range is moving northward
Established in Connecticut & MA
Eggs laid in cluster
Caterpillars feed in a group and destroy
single plants
Controlled by same products as other
caterpillars
Moth and group larvae photos by Dr L. T.
Kok Virginia Tech, Blacksburg, VA
Cross-striped
cabbageworm
(Evergestis rimosalis

25. Black Rot of Brassicas,
Xanthomonas campestris
pv. campestris
• Species is specific to
Brassicas
• Bacterial
• Plugs waterconducting
tissue with xantham,
mucilagenous sugar
Sources:
• Seed (0.3% of one seed lot can infect the
field)
• infected crops & weeds
• Crop residue (overwinter) esp. tough stems
• Survives in soil 40-60 days
• Spread in the field by rain, wind,
equipment, people, insects
• Enters through wounds and hydathodes
Conditions: warm moist (80-86 F optimum)
https://www.apsnet.org/edcenter/illglossary/ Photo credit: Holly Lange, Cornell U

26. Black Rot of Brassicas,
Xanthomonas campestris
pv. campestris
Bacterial
Plugs watercnduting tissue with
xantham, mucilagenous sugar
Symptoms
• V-shaped yellow lesion from leaf
marging toward center of leaf NOTE
black veins
• Mid-leaf dark patches between veins
• Petiole, stem
• Roots – affects turnip & rutagabag
• Followed by soft rot (smelly)

27. Black Rot of Brassicas,
Xanthomonas campestris
pv. campestris
• Spray at 7-10 day
intervals
• Preventatively
• At first detection
• When conditions
are favorable
Chemical control
Copper products
• Kocide (not OG)
• Organic: eg Badge X2 OG
Synthetic
• Copper + mancozeb: eg Mankocide
• Tanos
Plant defense activators
• Actigard 50 WG (Acibenzolar-S-methyl)
• Regalia BiofungicideOG (Reynoutria
sachaliensis Extract)

29. Alternaria leaf spot
(A. brassicae, A.
brassicicola
Species specific to Brassicas
Sources:
• Infected seed
• Crop residue (overwinter) esp
tough stems
• Infected crops & weeds
• Sporulates on infected residue
• Moved around by rain splash,
wind, equipment, people, insects
Conditions: cool, moist (60-78 F
optimum)
• advances in late summer & fall
• Develops in the canopy – long
leaf wetness periods

30. Alternaria leaf spot
Symptoms

31. Alternaria starts on lower leaves & inside
canopy, where leaf wetness is greatest

32. Chemical control
Synthetic
• Quadris (11), Quadris Top (11),
Endura (7), Bravo Weather Stik(M5)
• Switch (9&12), Inspire (3), Inspire
Super (3 & 9), Aproach (11), Rovral
(2), Cabrio
Organic/biofungicide
• Double Nickel Bacillus
amyloliquefaciens
• Has shown efficacy in two trials
Alternaria leaf spot

33. Alternaria and Black Rot on Collard
2013 UMass Trial, Sue Scheufele
Treatment and Rate (/A)x
ALS
Severity
y
(%)
BR Severity
z
(%)
Untreated Control………………… 1.4 ab 3.1 b
Quadris, 15 fl oz…………………… 0.1 a 1.8 ab
Actigard 50WG, 1 oz……………… 2.0 ab 1.5 ab
Serenade Optimum, 20 oz………… 1.0 ab 2.3 ab
Sonata, 4 qt………………………… 1.0 ab 1.6 ab
Double Nickel 55, 6 qt…………… 0.5 a 0.6 a
Actinovate AG, 12 oz……………… 2.3 ab 1.5 ab
Badge X2 DF, 0.75 lb……………… 2.5 ab 0.6 a
Basic Copper 53, 3 lb……………… 4.8 b 1.6 ab
Taegro, 5.2 oz……………………… 1.0 ab 1.4 ab
p-value 0.0233 0.0472

34. • Reduces vigor, growth, &
marketability; opens wounds
• Moves from mature onions
into late Brassicas
• Varietal resistance: http://veg-
guidelines.cce.cornell.edu/15framese
t.html; www.nevegetable.org
Onion thrips
(Thrips tabaci)
• Other hosts: Aliums, alfalfa, wheat, clover
• Rasping of epidermis becomes rough, brown
scar tissue. Cabbage: scars inside head

35. Thrips,
up close

36. • Organic:
• Spinosad (Entrust)
controls thrips, flea beetle, and
caterpillars
• Conventional:
• pyrethroids,
• nicotinoids,
• spinosyns (Radiant)
Onion thrips
(Thrips tabaci)

37. Downy Mildew of
Brassicas
(Peronospora parasitica)
Species is specific to Brassicas
Sources:
• seed
• infected living crops & weeds
• resting spores (long-lived, survive winter)
Conditions: cool, moist
• Rain, dew, fog, GH humidity
• Spores released, germinate & infect
Symptoms
• Irregular angular yellow-brown spots on
upper leaf
• Greyish white fluffy growth on underside

38. Downy Mildew of
Brassicas
Cultural Controls
Resistant varieties:
Broccoli (Marathon, Arcadia)
Field: 2-3 yr rotation
Wider crop spacing, use drip
GH: clean seed, clean growing
media, manage humidity and T
Sanitation: Remove or destroy
infected plants
Control brassica weeds
More Symptoms
Seedling: cotyledons
speckled, yellowing
Brocc., caul., cabbage:
infection of head
Dark brown areas on
surface
Internal dark or purple
streaks

39. Downy Mildew of
Brassicas
Spray preventatively or at
first detection
Confirm ID with diagnostic
lab
Synthetic fungicides
• oomycete specific
– Revus (40)
– Forum (40)
– Presidio
– Reason SC (11)
– Zampro (40 & 5)
Broad-spectrum
– chlorothalonil (Bravo Weather Stik)
– Ridomil (4)
– Ridomil Gold (4 & M5)
Organic
– Copper products

40. Swede Midge
• Scout, learn symptoms,
contact Extension if you
see it.
http://web.entomology.cornell.
edu/shelton/swede-
midge/index.html
Source: Christy Heopting, Cornell U

41. Swede midge: larvae
0.3 to 3-4 mm
Source: Christy Heopting, Cornell U

42. Many types of damage
Source: Christy Heopting, Cornell U

43. Cabbage Looper
Migratory – late summer
Scout as for other
caterpillars
Larger, ragged feeding
holes
If you see it in Brassicas,
also scout spinach, chard,
lettuce