Avoid the Tomato Blues
Jon Traunfeld
jont@umd.edu
College of
Agriculture and
Natural Resources
Isn’t six months enough?
• With planning and not that much more effort
• Harvest up to 10 or more months in MD
• Increase variety and flavor
Tomato (Solanum lycopersicum)
• Self-pollinating, tender herbaceous perennial;
produced as an annual crop around the world.
• Fruit is 95% water; flavor determined by free
sugars and acids, texture and growing conditions.
• Optimal growth and development occurs when
mean daily temperature is 70-75 degrees F.;
growth stops below 50 degrees F. Flowers and
fruits may drop when day temperatures >90
degrees F. and night temperatures >75 degrees F.
• Produces adventitious roots along stem.
• Growth habits vary –determinate, indeterminate,
patio, jointless.
• “What’s the best tomato?” They all grow well in
MD!
Tomato is tops!
• 2001-2013 HGIC answered 1765 e-mail
vegetable questions; 38% were for tomato.
– Vegetable abiotic plant problems: 53% tomato
– Vegetable disease problems: 62% tomato
– Vegetable insect problems: 30% tomato
– Vegetable weed problems: 11% tomato
Some IPM tips…
• Prevent problems and increase satisfaction by
picking at breaker to pink stage. Ripen indoors
unrefrigerated.
• People don’t notice the start of foliar diseases.
• “Wilt” (loss of turgor) is a misused descriptor.
• Don’t suspect late blight unless warranted.
• Disease resistance is variable (field vs. genetic).
• Is it ok to plant in the same location? (common
question)
Pick these…
Tomato plant & pest problems that
cause greatest yield loss
• Arthropods- spider mites, stink bugs
• Diseases- foliar leaf blights (early blight,
Septoria, gray leaf spot), late blight, fusarium
wilt
• Wildlife- mainly deer; also groundhog, squirrel
• Abiotic- poor growing conditions, climate
change, blossom-end rot, catfacing,
cracks/splits, pithiness
INSECTS AND MITES
Some effective organic insecticides
• Pyrethrins- controls or suppresses a wide
range of insects (Pyganic- 1.4%)
• Neem extract – suppresses beetles and
caterpillars
• Neem oil- insecticide and preventative
fungicide
• Spinosad- controls beetles, caterpillars, flies,
thrips
Some effective organic insecticides
(cont.)
• Bacillus thuringiensis- controls young
caterpillars; suppresses large caterpillars
• Surround- controls aphids, mites, caterpillars;
suppresses bugs
• Hort oil- controls aphids, mites, soft-bodied
immatures
• Insecticidal soap- suppresses aphids, mites,
soft-bodied immatures
Lady bird beetles chow down on aphids
Tobacco hornworm
I’m feeling sluggish these days… and
what’s with these hitchhikers?
The braconid wasps win!
Photo: Rosemary Noble
Brown and green stink bug (native) and
fruit injury
Brown marmorated stink bug (BMSB)
Photo courtesy: Susan Levi-Goerlich
Photo courtesy: Jane Hayes
Eggplant leaves coated with
Surround (kaolin clay)
Surround- kaolin clay
• 2006 research demonstrated significant flea beetle
suppression in eggplant- may be effective against
other pests.
• About $1 per lb. Rate: 1 cup/1 qt. water.
• Spray when leaves are dry. Apply thoroughly to all
leaf surfaces.
• Maintain white film coating on leaves; may take 2-3
applications. Re-apply if rainfall washes off white
coating.
• Can be used up to the date of harvest.
‘Juliet’ has tough skin- suffers less BMSB
feeding
Is it a problem? What can be done?
Climbing cutworm
Corn earworm a.k.a tomato fruitworm
Usually
enter at
stem end
Larvae mine and fold leaves and infest fruits.
Tomato pinworm
Spider mites love it hot and dry
Spider mites
Spider Mites
• 8 legged, non-insect; active on leaf
undersides. Two-spotted and European red
are primary pest species.
• Sucking mouthparts produce “stipples”;
tiny bleached areas on leaf surface; leaves
yellow and die
• Webbing is a sign of severe infestation
• Wide host range; many vegetable plants
• Thrive in hot, dry weather
• Many quick generations each year
Organic Management
• Mites like it hot, dry, and dusty. Hose off plants to
dislodge and annoy mites.
• Horticulural oil and insecticidal soap is most
effective on eggs. May be used if leaves are not
too damaged or hot to tolerate it.
• Excessive nitrogen fertilization increases mites
• Mites will migrate from neighboring weeds, so
keep weeds supressed. Clean up garden residues.
PLANT DISEASES
Cultural control strategies
• Grow resistant varieties.
• Clean up and compost plant debris at end
of season.
• Prune out injury; bag up badly infested
plants.
• Plant lots of flowering plants to attract
beneficial insects.
Disease ID codes help you select
resistant hybrid varieties
Totally Tomatoes
Early blight (fungal disease)- tomato
Advanced symptoms of early blight
Early blight- Alternaria solani
• Principal foliar disease of tomato; also attacks
potato, eggplant; a cosmopolitan pathogen.
• Splashes up to lower leaves and progresses up
plant; often appears with other leaf spot diseases.
• First symptom is irregular brown lesions with
bulls-eye pattern and yellow halo.
• Can spread rapidly with warm, humid weather
and defoliate plants.
• Over-winters in crop debris, wooden stakes, and
in soil.
Organic management
• Cultivars vary somewhat in susceptibility.
• Give plants more space; improved air
circulation.
• Remove badly infected lower leaves.
• Spray with fixed copper fungicide; other
organic sprays have not proven effective.
Manzate (mancozeb) and Daconil 2787
(chlorothalonil) are chemical fungicides.
Septoria leaf spot… another foliar leaf
spot disease
Cutting or
pruning out
suckers also
increases air
flow around
leaves ,
reducing
disease
incidence.
Late blight – Phytopthora infestans
‘Iron Lady’ (resistant
cultivar from Cornell
breeding program) is
available in 2013 from
High Mowing Seeds.
Late blight fruit
symptoms
Fusarium wilt of tomato
Fusarium wilt- brown
streaking under stem
epidermis; also visible
in many cases on
outside of stem.
Anthracnose- a fungal disease of ripe and
overripe fruit. (Another reason to pick fruit at the
“turning” stage).
ABIOTIC PROBLEMS
Frost/cold injury- leaf
whitening, small
gray/brown spots, or
blotches
Phosphorous
deficiency early in
season due to cool soil
and small root system
Edema- excessive soil
moisture early in
season, especially in
containers.
Blossom drop due to environmental stress
(usually high temp.). Photo courtesy: Jerry Brust, Ph.D.
Clopyralid
herbicide
injury
2,4-D herbicide
injury
Blossom-end rot
(nutritional disorder)
Epsom salt is NOT the
answer.
Muskmelon leaf
burned with
pyrethrum and
soap insecticide
“Catfacing”
Adventitious
(aerial) roots
Physiological leaf roll (heat stress)
Concentric cracking
Radial cracking
Graywall (blotchy
ripening); inside fruit
walls are brown or
black
Pithinessexcessive white
tissue
Green shoulder
Uneven ripening
Zippering
Garden located
next to large
driveway that was
resurfaced. Injury
from petroleum
products coming
off “liquid asphalt
cement”
Weird stuff…
ENJOY!
Resources
• Grow It! Eat It!
http://www.extension.umd.edu/growit
– We have all types of practical food gardening tips and
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http://www.extension.umd.edu/hgic
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