June 2020 - 18

Southeast's organic berry growers deal with diseases
ORGANIC
By Stephen Kloosterman
Associate Editor
Healthy plants in pleasant plantings
are the best way to deal with the
challenges of berry growing in the
Southeastern United States.
University of Georgia Associate
Professor and Extension Plant Pathologist
Elizabeth L. Little spoke in February
at the Southeast Regional Fruit and
Vegetable Conference on organic disease
management in small fruit.
" When it comes to disease, it's all about
prevention, " she said.
The Southeast's humidity and warm
weather make for an environment of high
disease pressure. Little said that in this
environment many organic-approved
fungicides have a low efficacy.
Nevertheless, many Georgia growers
do still grow organic berries for farm
markets and even commercial sales,
she said.
Strawberries are frequently grown on
a small scale, and the plants are often
treated as an annual, while some organic
blueberries are grown at a larger scale
for the wholesale market. Commercially
growing blackberries is difficult because
of cane infections and pest pressure
(especially spotted wing drosophila).
In general, it's important to battle
for berries by giving the plants the best
possible conditions for their biology,
she said. Plant health, sanitation and
genetic resistance are the basis of
organic disease management.
Strawberries
" Actually, strawberries go pretty well
here in southern Georgia, " Little said.
University of Georgia's Elizabeth L. Little spoke at the Southeast Regional Fruit and
Vegetable Conference Photo: Stephen Kloosterman
Disease challenges to strawberries
include botrytis, leaf spots, phytophthora
crown, anthracnose, fruit rots and
nematodes.
" Root knot nematode is a major
constraint to organic production in the
southeast, " she said. " They will build up, if
you don't pay attention. "
While nematodes should be monitored,
Millions of Trees
fungal diseases will sometimes crop
up following a rain event. Berries and
plants with diseases like botrytis must be
immediately removed from the area - not
just thrown out of the row, Little said.
Keeping the soils strong and clean is
Some Alternative uses of our
stakes that also have been
popular over the years:
1) Apples
2) Brambles, i.e. Blackberries
3) Tomatoes
4) Nursery and Ornamentals
5) Fencing
important. She recommends diverse crop
rotation, building soils and mulching.
Sun hemp can be used as a summer
cover crop for strawberries, she said (it's
problematic with blueberries because of
the required soil acidity). Sodded row
covers can be established with fescue
or various types of millet. Soils should
be improved prior to planting - it's not
necessary to add compost every single
year, but strawberries do enjoy strong soil.
Commercial growers in the Southeast
typically grow strawberries as an annual,
buying transplants in October to produce
a spring crop and then pulling them out
of the field, Little said. Getting clean,
high-quality transplants is vital. Mulching
can be done with organic materials, but
most growers use black fabric, which lasts
longer than plastic and unlike the plastic
can be left in place.
In Little's view, aggressive growing of
strawberries risks disease.
" You don't want to push the plants in
organic so they're big and the berries are
big and juicy and huge - a lot of nitrogen
and so forth, " she said. " You want to do
conservative fertilization.
" There's a tendency with strawberries
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to want to get those huge roots and those
big bushy plants, and you're going to get
more disease. And it's true with all of
these crops. You want to be an organics
conservative, especially with the nitrogen,
but all the nutrients. "
Blueberries
Selecting the right kind of site
is essential for organic blueberry
production, Little said. The ground
18 | FruitGrowersNews.com
should be acidic, with a pH of 4 or
5, and be well-drained and fertile.
Growers should look out for perennial
grasses such as Bermuda.
A strawberry rachis completely engulfed
by a gray mold fungus, Botrytis cinerea
Photo: Scott Bauer/USDA
She recommends growers avoid
replanting in old blueberry sites -
if they must, they should plant a
cover crop for 1-2 years. Selecting
high-quality plants is important, she
said, and native-derived rabbiteye
blueberries seem to grow the best.
Regular mulching with pine bark helps
with disease management, she said.
Poor site selection can lead to a host
of disease problems: Water-logged soils
will lead to root rot. Plant stress from site
problems can make them susceptible to
botrytis canker and dieback of the bush.
Little said that mummy berry is the
blueberry growers' major problem -
fighting the disease is mostly about
breaking the lifecycle of disease by
pulling out the spore-producing
" mummies " that sprout from infected,
dropped berries.
" Prevention is all about getting rid of
the mummies, " Little said. It's a major
problem for large growers. " I don't see
this in small, isolated plantings, but just
be aware. Don't let them build up. " FGN
http://www.FruitGrowersNews.com
June 2020

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