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How much things have changed
since our last bimonthly newsletter
went out! Hopefully much of these
issues are going to be behind us
soon, with Governor DeSantis issu-
ing Florida’s initial plan on returning
back to normal we’re all doing our
best to adapt while ensuring we con-
tinue to protect ourselves and our
neighbors. With the COVID issues
upon us extension had to make a lot
of changes rapidly in order to contin-
ue serving our client, hopefully many
of you were able to partake in the
numerous online programs offered
by all of our staff, from virtual in
home cooking demonstrations, virtu-
al 4-H, video horticulture consulta-
tions, and a range of gardening top-
ics being offered during the last two
months. For the near future we’re
going to be continuing with this vir-
tual programing to offer the most to
all of you; and perhaps this type of
training may become part of our
mainstay approach to increasing our
reach to the community. Things are
liking going to be in flux for a while
as we start transitioning back but re-
member we’re always here for you.
I hope you enjoy this edition of the
newsletter; as always we have some
interesting topics that can likely help
you correct or understand what
you’re seeing in your own yards!
In this Issue
Title Page
Leaf Wetness .................. 2
Spanish Moss ................. 3
Tomato Trouble ............. 4
MG Book Club .............. 5
Distance Education ........ 6
What to Plant ................. 6
“What’s That” Answer .. 6
For more information contact: UF/IFAS Extension Duval County
Chris Kerr - CKerr@coj.net - (904) 255-7450
Extension Update by Chris Kerr
Volume 2, Issue 3 May-Jun 2020
LARVAE
What’s That? Night Flying Adult Caterpillars in Squash Damage to Flowers
2
Leaf Wetness
Lawn diseases are a constant
issue that we have to deal
with to ensure our lawns re-
main at their peak. The
problem is so many home-
owners unknowingly are
putting their lawns into
harms way through their irri-
gation practices. I know for our
winter edition we discussed cali-
brating our lawn sprinklers, so if you haven’t read
that be sure to go back and incorporate that infor-
mation into your lawns cultural management pro-
gram.
Leaf wetness can be caused by several different fac-
tors including rainfall, dew, and overhead irrigation;
it’s basically the presence of water on the leaf’s sur-
face which is subsequently available for other organ-
isms to use. Those other organisms quite often in-
clude fungi and bacteria, but also many of our lawn
pests will benefit from this as well. The longer that
free water is present, the greater the chances of dis-
eases taking hold of the lawn.
The leaves are invariably going to get wet, but that
isn’t the crux of the problem. The issue is control-
ling the duration of the leaf wetness. Particularly for
fungi (hint: which happen to be the most common
culprit of lawn diseases in our area) the duration of
leaf wetness controls infective spore germination and
fungal growth. Each disease has a particular temper-
ature range and leaf wetness duration requirement for
infection to proceed. So anything we can do to re-
duce the leaf wetness duration will help to improve
the overall outcome.
We obviously can’t control the
rainfall, but what about dew?
While we might not be able to
easily control the formation of
dew, we actually can time our
irrigation to overlap the period
when dew is present. When
timed properly, the end result
actually produces larger water droplets
which roll off the leaves and reduces
leaf wetness durations. Following UF/IFAS irriga-
tion guidance, and your local irrigation ordinances,
are a great way to start managing lawn diseases be-
fore they even start. Irrigate on your assigned days,
no more than twice a week at 1/2” to 3/4” of water.
Water early in the morning while the dew is present,
if you water after this time you’re only extending
that leaf wetness duration, not to mention loosing
more water through evaporation. Here’s a quick
look at the seasonality and leaf wetness requirements
of some common lawn diseases:
Additional Reading:
Frequency of Residential Irrigation Maintenance Problems: (https://edis.ifas.ufl.edu/ae472)
Florida Turfgrass Irrigation Series: (https://edis.ifas.ufl.edu/topic_series_florida_turfgrass_irrigation_requirements)
Around the Yard by Chris Kerr
Above: Wet leaves promote fungal
disease in the lawn! (Photo UF/IFAS)
Disease Avg. Season Leaf Wetness Duration
Fairy Ring Feb. - Nov. Abundant Moisture
(High Organic Matter)
Large Patch Sep. - Apr. 48 hours
Take-All
Root Rot Apr. - Oct.
Abundant Moisture
(Over Irrigation)
Gray Leafspot May - Sep. 12 hours
(High Nitrogen)
Dollar Spot Sep. - Mar.
10 hours
(Low fertility, inadequate
irrigation)
3
Out on a Limb by Larry Figart
Spanish Moss- Friend or Foe:
Over the years, one of the most consist-
ently asked questions I have received
has to do with Spanish Moss. Does it
hurt the tree, and how can one get rid of
it. My answer is almost always the same
Spanish Moss Tillandsia usneoides, has
been co-existing with trees since the
dawn of time. Look at the image to the
right. It is the often photographed drive
to Wormsloe Plantation. Imagine the
image without Spanish moss? Now that
I think about it, that is probably too flip-
pant of an answer. There is probably a better way to
answer those questions.
Before we do that, lets look at Spanish moss a little
more closely. First, it is not a moss it is an epiphyte
(air plant) in the pineapple family. An epiphyte gets
its water and nutrients from the air, debris, and rain-
fall. If you look at Spanish moss under magnifying
lens you will see tiny scales. This is what it uses to
capture water and nutrients. You will not notice any
roots on Spanish moss. It does not have any. It simp-
ly hangs on trees and other things like utility wires.
Birds and wind spread small fragments of Spanish
moss. When the fragments land on a surface they
can cling to, they will continue to grow.
Spanish moss has a lot of uses. In the early 1900’s it
was used to stuff mattresses and cushions. The Great
Fire of 1901 in Jacksonville was started from a spark
that caught fire to Spanish moss on drying racks at a
mattress company near the corner of Davis and Bea-
ver Streets. In addition to stuffing mattresses it was
used as a binder for bricks.
Spanish moss is also utilized by wildlife. Bats roost
in clumps of Spanish moss. In addition to using
Spanish moss as nesting material, birds such as the
yellow throated warbler make their nests within the
hanging strands.
Now back to the tree question. Since it has no roots,
the Spanish moss is simply using the tree for support.
Most of the time that causes no harm to the tree.
What usually generates the call about Spanish moss
is the situation similar to the tree below. It is an old-
er crape myrtle. It is declining and the foliage is
thinning out. This gives the Spanish moss that has
blown from the oak behind it a perfect place to thrive
in the full sun. In a case like this I would say that the
moss is an aes-
thetic problem as
well as hamper-
ing the trees abil-
ity to recover. In
a tree that is still
a viable tree, re-
moval of the
moss would be
an option to con-
sider. When re-
moving moss,
the best way is to
pull it off. I have
seen folks use
rakes, pruning
saws, as well as broomsticks with nails hammered
into the end. For large trees consider using an arbor-
ist. There are some copper based products that have
labels for Spanish moss control. However the dead
moss will still need to be removed. If you use one of
those products read the label thoroughly before mix-
ing and applying. In the long run mechanical remov-
al is usually still the best option.
Photo by L. Figart UF/IFAS
Photo by L. Figart UF/IFAS
4
Growing in the Garden by Beth Marlowe
Tomato Trouble: Blossom End Rot
If the bottom end of the tomato (the one
that’s not attached to the plant) is turning black but the
rest of the tomato looks fine, you may have blossom
end rot (BER). This is not a disease, and it is not
caused by an insect pest. It happens when not enough
calcium has been making its way with water up from
the roots to the developing fruit. Lack of calcium
causes cell walls in the fruit to break down, leading to
invasion by a secondary pathogen. BER can also af-
fect peppers and cucurbit crops so if you’re growing
either of those pay attention to these potential issues as
well. Once you have BER on a fruit, that one can’t be
fixed. You can, however, prevent most cases of BER
through sound management practices.
You may think this means you simply
need to add more calcium to the soil to solve the prob-
lem. Although this may be a solution to the problem,
especially in a raised bed or container, our native soils
often have plenty of calcium. And our irrigation water
often has more. So how can there be a deficiency in
the fruit? There are three main causes:
1. Inconsistent watering. Calcium is transported up
through the plant in water. If watering is erratic,
then supplies of calcium to the developing fruit are
also erratic and may be missing when needed.
2. Over-application of nitrogen. Excessive nitrogen
can cause excessive leaf growth, redirecting water
(and calcium!) from the developing fruit to the
leaves. The ammonium form of nitrogen can also
inhibit calcium uptake.
3. Unavailability of soil calcium. This can be due to
an excess of soil magnesium or potassium, lack of
adequate or soil moisture to move the calcium, or
even damage to the root tips that take it up.
Once BER is apparent, solutions are
limited. You can try adding calcium to the soil, but if
lack of soil calcium was not the problem, adding more
will not fix it. Applying calcium solutions to the
leaves is generally more effective at preventing BER in
these situations, however it still won’t help correct any
damage that has already occurred. Harvest the dam-
aged fruit and change cultural practices going forward.
Water consistently. Add mulch to help soil retain
moisture. Get soil nutrients tested and amend or re-
duce fertilizer applications. Avoid damaging roots.
Blossom end rot is definitely a case where an ounce of
prevention is better than a pound of cure!
Photo Credit: nwdistrict.ifas.ufl.edu
Additional Resources:
Blossom End Rot in Bell Pepper: (https://edis.ifas.ufl.edu/ss497)
Tomato Disease in Florida Vegetable Gardens: (http://edis.ifas.ufl.edu/pp121)
Landscape and Vegetable Garden Test Form (http://edis.ifas.ufl.edu/ss187)
5
JOIN US!
MASTER GARDENER VOLUNTEER BOOK CLUB!
Who: You! The program is brought to you by the
Florida Master Gardener Volunteer (FLMGV)
program, but anyone can participate.
What: We’ll be reading The Foodscape Revolution, by
Brie Arthur. Foodscaping means incorporating
edible plants into your existing home land-
scape.
When: Begin reading now. The FLMGV Program will
host a webinar to discuss in May. Check the
Duval County Extension website or FLMGV
social media channels for the exact date.
Where: Join us online from the comfort of your own
home.
Why: It’s a great way to connect with other garden-
ers from all over the state who are interested in
growing more food at home!
How: Simply purchase or borrow the book and follow
us on Facebook or Instagram. See the blog at http://blogs.ifas.ufl.edu/
clue/2020/04/17/announcing-the-florida-master-gardener-volunteer-book-club/
for more details.
Images courtesy FLMGV Program
6
Distance Learning Resources
Virtual Vegetable Gardening Series
Fridays, April 3 - June 5, 2 p.m. - 3 p.m. Stuck at home and looking to grow more of your own food? This is an excellent introductory course on a range of vegetable gardening topics, access via Zoom for free from the comfort of your own garden! https://www.eventbrite.com/e/101647614752
4-H Virtual Embryology
May 13 - June 3 Receive access to daily videos with updates on chick embryo development, vo-cabulary, science experiments to try at home, and other hands-on activities. There will also be a live stream of chickens hatching! 4-H Membership is NOT required, all are welcome to participate at no cost. Program is geared towards K-5 students but additional resources are available for grades 6-8. https://www.eventbrite.com/e/102888014822
Lawn Management Webinar Series
Friday May 15 and May 22, 11:30 a.m. to 1:15 p.m. Maintaining a healthy vibrant lawn isn’t always easy, but it shouldn’t be difficult either. Learn about a range of topics related to lawn care including the selection, identification and cultural management of turfgrasses, chemical considerations, damaging lawn pest and diseases of the Florida lawn. https://www.eventbrite.com/e/104144769810 Don’t forget UF/IFAS has a lot of gardening resources available online including: Extension Electronic Data Information Source: https://edis.ifas.ufl.edu UF Entomology Featured Creatures: Entnemdept.ufl.edu/creatures Need to find a UF Expert? : https://ics.ifas.ufl.edu/experts/
It’s the pickleworm! This is a very common pest in the backyard garden on a range of cucurbit crops including cucumbers, squash, cantaloupe, pumpkin and watermelons among others. This one can be a bit more difficult to control than some of our other common pests if we’re not paying close attention and scouting regularly. The issue is, the pickleworm feeds internally, so most of our chemical and biological controls are less effective. In fact, for products such as Bt.to be effective, you’ll have to start regular applications at first bloom through har-vest. Some of the thicker rind curcurbits can fair better once the rind thickened but these caterpillars often start by attacking the blooms and then burrowing into the fruit before the blossom drops. They can feed rather dis-cretely and cutting into your vegetables later can lead to a big surprise. Their feeding will quickly render those vegetables in-edible. Another option for small plantings is to cover them with a raised netting at night, the adults only fly at night so this can limit their ability to lay eggs, just remember to remove the netting in the morning so pollinators can reach the flowers.
Further Reading:
Pickleworm, Diaphania nitidalis (Stoll): (https://edis.ifas.ufl.edu/in321)
What to Plant in
May & June
It’s starting to get hot so
make sure you’re using
plants that can handle our
Florida weather.
Annuals - Angelonia, celo-
sia, coleus, portulaca, sal-
via, ornamental peppers,
vinca and wax begonia.
Bulbs - Daylily.
Vegetables - Okra, south-
ern pea, sweet potato and
swiss chard.
Herbs - Basil, oregano, tar-
ragon, rosemary.
Keep monitoring those
pests populations and im-
plement appropriate con-
trols! Don’t forget to put in
some floral nectar sources
to encourage the beneficial
insects!
What’s That?
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