The Garden Spade November 2017 Cleaning Up After Plant Disease and Pests Donna Aufdenberg, MU Extension Horticulturist Subscribe Now! Receive a monthly email with a direct link to “The Garden Spade”. Send email to [email protected]An equal opportunity/access/ affirmative action/pro- disabled and veteran employer **In This Issue** Cleaning up After Plant Disease and Pests What Is It? Quick Apple Facts Houseplants Winter Survival of Plants and Insects Stratifying Seeds Upcoming Programs “Reliable, Responsive and Relevant Information for the Missouri Gardener” We have had a trying year for gardening. Many gardens and landscape areas have ended the garden season on a sour note with lots of disease and problems. Many gardeners are wanting to know at this point, what can I do to clean things up and not face some of the same problems again. In the vegetable garden, compost or turn over any plant debris that is not diseased as soon as possible after harvest to begin the break down process of organic matter. Pull or pick up any diseased plants and GET RID OF THEM! Send them to the ditch, to the trash, or burn them. Anywhere but near or in the garden area will do. Do not plant vegetables from the same family of plants at the same location for 3 to 5 years. Plants within the same family need to be a minimum of 10 to 15 feet away from the location of the diseased crop. On trees and shrubs, if leaf spots and diseases were a problem, make sure to rake up and remove all leaves from the site. If the area is too big to remove the leaves, mulch leaves with a lawn mower to break up the leaf pieces to speed up the breakdown of infected plant. Remove any branches or twigs that are broken, look unusual or have any cracks, shrunken or discolored areas. In perennial flower gardens, if leaf spots or blights are present, cut stems at the soil level and remove all infected plant parts. If no disease exists, then removal is not necessary but optional. If you Continued to page 2 Leaf spot symptoms of early blight on tomato. M. Grabowski, UMN Extension
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The Garden Spade November 2017
Cleaning Up After Plant Disease and Pests Donna Aufdenberg, MU Extension Horticulturist
Winter Survival of Plants and Insects Michele Warmund, MU State Fruit Extension Specialist
With winter approaching, plants are acclimating and insects are altering their behavior and physiology in
response to shorter day lengths and cooler temperatures. Plants are accumulating sugars and proteins as
they become dormant for the cold winter months ahead. Overwintering plants survive temperatures below
32°F by tolerating or avoiding freezing. Some plants, such as zoysiagrass, survive by tolerating ice
formation in spaces between cells. Other plants, including fruit trees grown in Missouri, survive low
winter temperatures by avoiding freezing. Water inside freeze-avoiding plants remains in an unfrozen state
due to supercooling.
Insects utilize one or more methods for winter survival including migration, freeze avoidance or freeze
tolerance. Some insects avoid cold weather by migrating to warmer climates. Probably the best example of
migrating insects are Monarch butterflies that begin flying south in late August to overwinter in Mexico.
Green darners, a common species of dragonflies, also migrate to Texas and Mexico to avoid freezing
temperatures. Another way insects avoid the cold is by seeking shelter. For example, adult Asian lady
beetles overwinter in cracks and crevices in roof shingles, windows, and siding on structures. All life
stages of European honey bees overwinter inside hives. Leaf litter is another common shelter for
overwintering insects such as bean leaf beetles, stink bugs, and grasshoppers. Other insects can be found
within bud scales (mites) or under loose bark of trees (codling moth larvae), in leaf litter, underneath rocks
(pillbugs), or in the soil (Japanese beetles) during winter (Figure 1).
Many insects spend the winter in a state of dormancy called diapause. In
the fall, shorter day lengths and exposure to cool temperatures trigger
hormone production, which lowers insect metabolism and their energy
requirement. When conditions become favorable near spring, insects
resume their activity. Insect eggs, larvae, pupae, or adults can undergo
diapause, depending on the species.
Freeze-avoiding insects lower the temperature at which their body fluids
freeze. Thus, they can withstand temperatures below 23°F. Some insects avoid freezing by emptying their
gut to prevent internal ice formation. Certain insects can also produce antifreeze proteins in their
hemolymph (body fluid) that bind to ice crystals during their formation to prevent crystals from growing.
Other types of antifreeze compounds synthesized by insects are polyols and sugars, which lower the
freezing point of their hemolymph. Glycerol is a common type of polyol and sorbitol is a sugar that lowers
the temperature at which an insect freezes. Codling moth and emerald ash borer larvae and forest tent
caterpillar eggs survive winter by freeze avoidance.
Freeze-tolerant insects are able to withstand the formation of ice internally. In the fall, ice nucleation-
active agents in the insect's hemolymph or in other parts of the body promote non-lethal ice formation
extracellularly (i.e., outside cells) at temperatures usually between 23 and 14°F. Even though ice forms
within the insect, it is non-lethal. Woolly bear caterpillars are an example of a freeze-tolerant insect.
For the upcoming winter, the National Oceanic and Atmospheric Administration (NOAA) is predicting a
weak La Nina event. Thus, there is much uncertainty in the forecast for Missouri weather. At best, we can
look for insects seeking shelter and follow their lead to avoid freezing.
Figure 1. Eriophyid mites over-wintering in an elderberry bud
The Garden Spade November 2017 · 6
Time to Stratify Seeds To Start Seedlings in Spring Donna Aufdenberg, MU Extension Horticulture Specialist
Seeds need the right environment to start: temperature, moisture, air and proper light conditions. What
happens when all these things are right but germination still does not occur? Well, some seeds need to
overcome seed dormancy through STRATIFICATION.
Stratification is cold, moist chilling of seeds to meet a chilling requirement in order to germinate. Some
seeds require a period of 3 to 6 months at temperatures below 40 degrees Fahrenheit. This requirement
mimics the winter season. Lee Stivers from PennState Extension explains, “For
example, the membrane within the seed coat of some seeds forms a barrier that is
permeable to water but not to oxygen. Cold temperatures allow oxygen to get into
the seed, while warm temperatures prevent oxygen uptake. Cool temperatures also
allow the seed to digest some of its food reserve, giving it energy. For these seeds,
putting them in the refrigerator for a specific period of time allows them to gain
sufficient oxygen and energy to germinate (Colorado Seed Laboratory 2009).”
So, how does one go about stratifying seed? Seeds can be placed in moistened, (sterile) sand, sawdust or
vermiculite inside a plastic bag. Avoid excessive moisture. Keep seeds in a place that doesn’t freeze but
stays below 40 degrees Fahrenheit for the recommended amount of time. A refrigerator is suitable. Check
bags weekly for mildew or dryness.
Once stratification period is met, sow seeds in larger pots or open packs by sprinkling contents on top of
loose potting mix and gently watering in. A thin layer of soil or sphagnum peat might be needed on top of
some types of seeds. It is best to consult books and publications on species specifics.
What Is It? Katie Kammler, MU Extension Horticulture Specialist
This is a pumpkin that is called Musquee de Maroc.
This is the first year that I grew this variety and it made it despite
the drought in the middle and end of the growing season. This is a
moshata type pumpkin so it is closely related to butternut squash
and field pie pumpkins. These types tend to have longer maturity
dates so they will be one of the last squash ready for harvest. I
really like the look of the warts on this tan pumpkin. I had quite a
few and they all were a little different in shape and wartiness. It is
a fun new pumpkin to try in next year’s garden! I bought the seed
from Baker Creek Heirloom Seeds.
Baker Creek Catalog says, “The stunning, round to bell-shaped
fruits are terra-cotta to buff-colored, and warted very attractively.
You'll want to use this one in centerpieces and displays before you
consign it to the kitchen! A commercial variety in north Africa.”
Seedlings, Picture from PennState Extension
The Garden Spade
November 2017 · 7
Upcoming Events The following Master Gardener meetings are held each
month. All are welcome to attend. Please contact your local extension office to confirm location of next meeting.
Parkland MGs - 1st Monday, 6:30pm, Farmington Public Library
Poplar Bluff MGs - 1st Tuesday at 6:00 pm. Call 573-686-8064 for the location.
Ste. Genevieve MGs - 2nd Thursday, at 6:30pm, Ste. Gen. County Extension Center
Cape Girardeau MGs - 3rd Thursday at 7:00pm, Cape County Extension Center from Nov to March and Shawnee Park Center from April to Sept. Call 573-238-2420 for questions.
Perry MGs - 4th Monday at 6:30pm, Perry Co. Extension Center