Cornell Cooperative Extension of the
~~~Commercial Horticulture Electronic Newsletter~~~
Volume 7,
Issue 3
August 20, 2007
Participating Counties: Orange * Dutchess * Putnam *
Editor: Rosemarie S. Baglia
http://www.cce.cornell.edu
In
this Issue:
Thrips Biocontrol with Predatory Mites
The NYS IPM program has been evaluating the use of predatory mites for thrips
control in bedding plants for over a decade. The results, both in
production and retail settings, have been promising enough that we encourage
other growers to utilize this approach.
The benefits of using biocontrol are numerous. The lack of an REI
(re-entry interval) means they can be applied during normal working hours
without disrupting other greenhouse tasks or incurring the added expense of
overtime for late evening/night spray applications. No pesticide license
is needed and applications are simple and straightforward. The applicator
incurs none of the risks or general unpleasantness associated with mixing,
handling and applying pesticides. Resistance is not an issue but use of
the mites can prolong the usable life of other thrips insecticides by reducing
our reliance on them.
While there are many positive benefits, we realize that a lack of confidence in
the mite’s ability to successfully control thrips can be a strong barrier
against adopting this practice. This is especially understandable if the
grower has had the unfortunate experience of losing large numbers of plants to
an outbreak of INSV, a virus that can be carried and spread by thrips.
How it works:
The predacious mite, Neoseiulus cucumeris, (often just called Cucumeris
by greenhouse growers) feeds on young thrips and will also feed on spider mite
eggs or even pollen. The idea is to flood the plants with these miniature
eating machines so few, if any, thrips survive to reproduce.
How to implement:
The mites come in two formulations, sachet and loose. The sachets are
essentially small paper bags that contain some predatory mites (approximately
300), bran, and bran mites. The predatory mites feed on the bran mites
and breed. Once set out in the greenhouse a corner of the bag is removed
and, as their numbers build, the predatory mites crawl out and spread over the
crop. The sachets are set out at rate of 1 bag per 25 sq/ft. (approximate
cost for a 2500 sq/ft house is $.03 per sq/ft per application). While
they may continue to emerge for 12 weeks, most have emerged after about 6 weeks
therefore it takes at least two applications to cover the bedding plant
cycle. Alternatively you might go with a lower initial rate and set out
additional, fresh, bags every two weeks. This method has worked
reasonably well in our trials and only one spray application for thrips was
needed all season (total cost of mites for a 2500 sq/ft house including
shipping charges was $.05 per sq/ft. or $125. ).
The second, loose, formulation has a high number of predators in a container
with bran and enough bran mites to keep them alive during shipping. The
bran and mites are sprinkled over the crop at a rate of 17-25 predators per
sq/ft (40,000-60,000 for a 2500 sq/ft house (approximate cost $.01 per sq/ft
per application). As the predators don’t reproduce to any great extent once
released, weekly or bi-weekly repeat applications are recommended. Just
as in a chemical control program, thrips levels should be monitored with yellow
sticky cards.
Once the predators arrive they should be checked for viability. Exposure
to extreme cold or heat may have destroyed them during shipping. After
gently shaking the container, place a small amount of the bran-mite mixture
onto a piece of paper (dark colored paper works best). Examine the
brownish-pink predators and white bran mites with a hand lens for signs of
movement. Don’t store the product, its advisable to get them into the
houses within a day of arrival, two at most.
Pesticides & Mites:
While the predators may keep your thrips levels low enough that you never need
to spray for them (the lead grower that participated in the study has only made
two applications for thrips in the past six growing seasons!), you may have to
spray for other pests, such as aphids or spider mites, or for disease
control. Since the predators are living creatures, it’s important to know
what, if any, effects pesticides will have on them. In general,
fungicides have not shown any adverse effects on the mites so disease control
is usually not an issue. However, insecticides and miticides vary greatly
both in their initial and residual effects. For example, the commonly
used insecticide, Orthene, will kill the predators and its effect lasts up to
10 weeks so its use should be avoided if you wish to use predatory mites.
Other insecticides may be harsh initially but have little or no residual effect
so can be used just before a release. A few have no immediate or residual
impact. A database of pesticides and their effects on predatory mites can
be found at: http://www.koppert.nl/e0110.html.
(CHECK THIS!)
Conclusions:
It should be noted that the predators are not well suited to stopping a raging
infestation. If you already have high thrips numbers, prior to
introducing the mites you should first knock them down with a compatible
insecticide such as Conserve. The mites also have a more difficult time
controlling thrips if you aren’t taking other thrips suppressive steps such as
controlling weeds under the benches. With the great variation among
different greenhouses and plant mixes the formulation and rates appropriate to
your operation may need to be adjusted. If you are considering using the
predators next season but have additional questions or would like assistance in
trialing the predators please contact any member of the Ornamentals IPM Team.
Written by Gary Couch, NYS IPM, glc15@cornell.edu.
The Basics of Alternative Herbicides
There are a variety of herbicide products, based on naturally occurring
compounds that are of interest as alternatives to synthetic herbicides.
These products include corn gluten meal, vinegar, and various plant oils as the
active ingredients. There are several soaps used as herbicides, which,
while not naturally occurring, are often considered alternatives, as
well. Although these herbicides are considered least-toxic alternatives,
they require proper handling and can be skin, eye, or lung irritants. As
with all herbicides, applicators must follow the application requirements on
the label, including use of personal protective equipment.
What are they? Corn gluten meal is a by-product of the corn milling
industry. Acetic acid is the basic ingredient in vinegar. (However,
the acetic acid levels in household vinegar are not high enough to use it as an
herbicide.) Eugenol is an oil extracted from plants, especially from clove,
nutmeg, cinnamon, and bay leaf. Pelargonic acid is found in oil of
pelargonium, among other plant sources. Soaps used as herbicides are
potassium salts of fatty acids, which, while not naturally occurring, are
considered less toxic.
Corn gluten meal contains compounds that inhibit seed germination, so in
certain settings it has some potential as a pre-emergence herbicide.
However, part of its activity in weed control, particularly for turf, is as a
nitrogen source, encouraging rapid grass growth to out-compete weeds. It
has no activity on established weeds and will interfere with seed germination
of desirable plants as well as weeds, so should be applied after desired plants
have true leaves and are 2-3 inches tall.
Acetic acid and eugenol interfere with the action of the cell membrane,
allowing cell contents to leak out and causing the death of the cell.
Pelargonic acid and soaps remove the waxy cuticle of plant tissue, which allows
the cells beneath to dry out and die. In both cases, herbicide
application results in a burning of the leaves, which can be seen almost
immediately. There is no movement of the active ingredients throughout
the plant, so good coverage of the foliage is essential for weed control.
Also, mature perennials and other plants that can regenerate from the root
system will not be killed because the herbicide is not translocated to the root
system. These herbicides are non-selective, so they will damage the
foliage of any plant contacted. They are most useful for control of
young, actively growing, annual weeds in a situation where desirable plants are
either not yet present or can be protected from the herbicide.
There are many different products available with these chemistries and the
concentration of the active ingredient can vary dramatically. Users
should check both the amount of active ingredient in the concentrate or
ready-to-use formulation and the appropriate dilution ratio for the situation,
as described on the label. Cost per application can be high for some
products, especially if reapplication is necessary for complete control.
It should be noted that not all of the products described are labeled for
certified organic food crop production. Users should check the OMRI list
or other lists of products accepted under the National Organic Production (NOP)
regulations. There is no equivalent list of products labeled for organic
production of ornamentals.
The information in this article was taken from two fact sheets in the
Alternative Pest Management Series, by Leslie Weston and Elizabeth Lamb.
The complete fact sheets are available at the Landscape Horticulture Program
Work Team website under Resources ( http://www.entomology.cornell.edu/Extension/Woodys/LandscapeHortPWT/AlternativePesticideFactSheets.html
).
Written by Betsy Lamb, NYS IPM, eml38@cornell.edu.
Canna Viruses
Their bold foliage and bright flowers help make cannas a popular plant, giving
a tropical look to Northeast gardens. Unfortunately in the last couple of
years two virus diseases: Canna Yellow Mottle Virus and Canna Mosaic Virus have
impacted the production and sales of this popular plant. Symptoms include
stunting and yellow and brown leaf flecks and yellow streaks along veins.
Normally diseases show up in a spotty or clustered pattern in a greenhouse
crop. Rarely are all plants infected unless the stock material arrives
infected. This spring an alert greenhouse grower in NY noticed that all
his cannas of one variety, Rosemond Cole, seemed stunted and had some foliage
discoloration. Working with his extension educator he had the plants
tested and they were found to have both Canna Yellow Mottle Virus and Canna
Mosaic Virus. He was not alone; this problem was widespread this year.
Spread of these viruses can occur by any type of a mechanical injury that moves
plant fluids. Handling during propagation and division is of particular
concern. In addition aphids can transmit Canna Mosaic Virus but insects
have not been found to transmit Canna Yellow Mottle Virus.
Plant virus disease infections are systemic in the plant and the only treatment
is to remove and destroy infected plants. It is very important to use
only virus free rhizomes or plants for production. Ask your supplier if
the plants you are considering purchasing have been tested to confirm they are
virus-free.
Written by Brian Eshenaur, NYS IPM, bce1@cornell.edu.
Value of New York Floriculture Production Increases
Press release from Kathy King, National Agricultural Statistics Service, www.nass.usda.gov/ny
New York floriculture production ranked fifth in the nation for total
commercial sales in 2006, according to Stephen Ropel, Director of USDA’s
National Agricultural Statistics Service, New York Field Office. Value of sales
increased from a year earlier for cut flowers, potted flowering plants, and
propagative materials. The overall value of commercial sales increased 3
percent to $207 million. Bedding and garden plants continued to be the
highest component of the total value of sales at $109 million. Potted
flowering plants were second with a value of sales of $50.3 million, an
increase of 1 percent. Propagative materials ranked third at $17.5
million, an increase of 52 percent from 2005.
The number of commercial growers decreased for the fourth consecutive
year. During 2006, there were 721 growers. The open ground area
used to produce floriculture crops in the state was up 19 percent to 950
acres. Greenhouse space for operators exceeding the $10,000 sales level
increased 5 percent to total 26.0 million square feet in 2006. This
increase pushed the total covered area (greenhouse plus shade and temporary
structures) up to 26.5 million square feet, 5 percent more than 2005.
Nationally, the total wholesale value of floriculture crops grown by operations
exceeding the $100,000 sales level reached $3.83 billion in 2006, down 3
percent from the revised 2005 total. These operations, which comprise 46
percent of all growers, account for 96 percent of the total value of
floriculture crops. Bedding and garden plants wholesale value, at $1.79
billion, is the largest contributor to the value of production, down slightly
from the previous year. Potted flowering plants value, at $620 million,
is down 3 percent from 2005. The foliage category is valued at $543 million
for 2006. This is down 19 percent from the revised 2005 estimate.
Value of cut flowers, at $411 million, is up 4 percent, while cut cultivated
greens, at $109 million, is up 2 percent from 2005.
Additional details are available in The Floriculture Crop Summary - 2006",
released July 26, 2007. It is available on the Internet at www.nass,usda.gov or by
calling 518-457-5570.
Submitted by Donna Cooke, Cornell Cooperative Extension Rockland County
Fungal Control for Root-Eating Insects
Root-eating insects could soon be eating themselves sick if their favorite food
has been treated with a fungal biocontrol agent.
Agricultural Research Service (ARS) scientists in
Current control methods involve applying large amounts of entomopathogenic
fungi to the soil in which at-risk plants grow. This approach is both
costly and inefficient. ARS entomologist Denny Bruck has discovered that
using plant roots as an underground "delivery system" for the fungi
is cheaper and more effective than broad distribution. He and his
colleagues in the Corvallis-based ARS Horticultural Crops Research Unit tested
several fungal strains and found that some of them thrived in the area
immediately surrounding a plant's roots. In fact, some fungal populations
were 10 times denser there than in the surrounding bulk soil.
In one study, Bruck and his colleagues dipped plant roots in solutions
containing spores of Metarhizium anisopliae, a fungus that occurs
naturally in fields but not in container-grown plants. They observed that
black vine weevil larvae died after eating the fungus-treated roots.
Dipping roots in entomopathogenic fungal solutions may prove to be economical
and efficient, because growers would only need to treat that specific area.
Another study demonstrated that black vine weevil larvae actually prefer the
colonized plant roots, so they are more likely to snack on roots that will harm
them. Perfecting a fungal solution to root-eating pests could potentially
save the West Coast nursery industry millions of dollars every year.
Written by Laura McInnis, USDA-ARS, August 2007. To read more, visit: http://www.ars.usda.gov/is/AR/archive/aug07/insects0807.htm.
Submitted by Rick Harper, Cornell Cooperative Extension - Westchester County
Forestry Seminars on the Internet
Are you interested in learning more about forests, forest management, and
forest ecology? Do you have a computer with access to the Internet?
Then you need to know about Cornell's ForestConnect Internet Forestry Seminars,
designed for forest owners, foresters, and practitioners. On the third Wednesday
of each month, you can learn about topics that range from how to select trees
for firewood cutting, to vernal pools, to arranging a timber sale. Extension
specialists provide live and interactive presentations on the Internet (current
technology is a bit much for modem users however). All you need to do is
register at www.ForestConnect.info.
Registration is free and easy to complete. Seminars are at noon
and repeated, live, at 7:00 PM.
The ForestConnect Internet forestry seminars are broadcast (called a webcast)
to your computer on a webpage. The URL for the webpage is provided after
you register and about a week before a webcast (see above). The webcasts
include a PowerPoint presentation and the opportunity to ask questions and
interact with the presenter. Each webcast has written materials used to
supplement the presentation and provided, also free, at the ForestConnect
website. Previous webcasts have been saved and are available at www.ForestConnect.info for
viewing. This technology is made possible through Cornell Cooperative
Extension.
Future Topics:
More information is
available at the ForestConnect website at http://www.dnr.cornell.edu/ext/forestconnect/.
Or call Diana at 607-255-2115.
We have seen some hot weather over the month of
July and the first part of August (2195 GDD slightly above normal for
August 19) with generally adequate intervals of rainfall (25.07")
thus far in the season. Our phone calls have included questions and
reports about summertime diseases on turf including Pythium, Brown patch, Leaf
spot and Dollar spot. While it is during the month of August, that our
cool-season turf grasses often temporarily turn consistently brown and go
'dormant', we’ve had enough rain to keep most of our lawns green and growing
thus far. If you have areas of turf that have historically been host to
populations of White grubs, August is the time of the year to consider
inspecting those sites for the presence of early instar larvae - .
During our field site visits, we have observed many of the usual diseases that
occur on ornamental plantings during this time of the year including Powdery
mildew on Lilac, Phlox, Peony, and other ornamentals, and Black spot on
Roses. Feeding damage from pests active earlier in the season like Spruce
spider mite (SSM) can be observed on plantings such as
We have received a number of samples in our lab including, Boxwoods damaged by
Boxwood leafminer, and Apples that had been damaged by Codling moth and
Worthy of special mention was a pest that was found to be inhibiting flower
production on Roses - this was determined to be the insect known as Rose midge
and you can read more about it at: http://www.extension.umn.edu/distribution/horticulture/components/6953_03.html
.
Written by Rick Harper, Cornell Cooperative Extension - Westchester
County
Dutchess County
Well, it's official! Mile-a-minute weed, Polygonum perfoliatum
L., has arrived in
Another invasive pest has invaded
As I drive along the
Submitted by Stephanie D. Mallozzi, Cornell Cooperative Extension Dutchess
County
Ulster County
Cicada killers appear to be out in
full force these days. Many homeowner samples of these rather large
digger wasps have shown up at our diagnostic lab over the past two weeks.
Cicada killer wasps like to dig their nests in bare, sandy soil in full
sun. They catch cicadas and drag them down into their burrows to feed
their larvae. The larvae overwinter in the burrows and emerge the
following summer. The wasps are not particularly aggressive and typically
will not sting. Sometimes these wasps will build up in favorable sites
and control may be necessary to avoid potential stings. Building up a thicker
turf will make the site less attractive for nesting.
Stinkhorn fungi have been appearing in yards and fields recently. They do
not cause disease problem to plants growing near them but they do emit a foul
order. These curious-looking mushrooms simply live on dead organic
matter, such as wood chips and crop debris. A stinkhorn begins life as an
egg-like object in the soil, about the size of a golf ball. As the fungus
develops, a stalk appears topped with a slimy cap coated with a mass of
olive-green to brown spores. They range from about 4 to 8 inches in
height. They are not poisonous, but are classified as inedible.
Their stinky aroma alone would keep most people at a distance.
Submitted by Teresa Rusinek,
Plant samples have been flooding the diagnostic lab this past month.
One interesting pest that came in this week was a mulberry tree branch with a
nest of fall web worms. Very jumpy little creatures- they all seem to
jump at once as if all of their minute brains were connected! Japanese beetles
are still around but starting to decrease in numbers. Scattered heavy
rains have kept things green in most areas of the county.
Submitted by Rose Baglia, Cornell Cooperative Extension Orange County
Putnam County
Giant Hogweed and Mile-a-Minute weed, both noxious invaders, are present
and thriving in
Reports and samples of cicada-killer bees and other ground nesting bees are
coming into the lab daily. We are also seeing lots of leaf scorch issues
on Japanese maple after the intense weeks of summer heat just past.
The damage done by locust leaf miner, which at this time looks rather dramatic,
has spurred a lot of concern from homeowners whose large Black locusts (Robinia
pseudoacacia) are looking ratty and tired. Information about its
lifecycle can be found in Johnson and Lyons book, "Insects that Feed on
Trees and Shrubs". Photos of this leaf-mining beetle (Odontota
dorsalis) can be viewed at http://www.forestpests.org/southern/locustleafminer.html
Submitted By Jennifer J Stengle, Cornell Cooperative Extension Putnam County
Tri-County
Nursery/Landscape Association In Conjunction With Cornell Cooperative Extension
Present 2007 Calendar of Events
September 11
Golf Outing At Winding Hills
Jim Presutti (845) 567-1611
October 13 & 14
Small Farm and Rural Living EXPO- Ulster Fairgrounds
Rose Baglia (845) 344-1234
November 13 -15
Green Industry
Show- Rochester
Jan Jansen (845) 651-4106
December 1
Holiday Party
Kevin Shuback (845)
651-4074, Jan Jansen (845) 651-4106
All Dates Subject to Change. For more information or to become a member
contact: Kevin Shuback at (845) 651-4074.
Cornell Cooperative Extension County Commercial Horticulture
Educators
Dutchess: Stephanie Mallozzi, sdm10@cornell.edu, 845-677-8223
x 104
Orange:
Rosemarie Baglia, rsb22@cornell.edu, 845-344-1234
Putnam: Jennifer Stengle, jjs95@cornell.edu, 845-278-6738
Rockland: Donna Cooke, dmc72@cornell.edu, 845-429-7085
Ulster: Teresa
Rusinek, tr28@cornell.edu, 845-340-3990
Westchester: Rick
Harper, rwh26@cornell.edu, 914-946-3005
Sullivan: Marianna Quartararo, mdq2@cornell.edu, 845-292-6180
x 112
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