“WHAT’S HAPPENING?”
University of Tennessee - Agricultural Extension
Service
Entomology
& Plant Pathology - EPP #60
Volume No. 12 - August 19, 2004
Pine Sawflies
Frank A. Hale
Sawflies are related to bees,
wasps and hornets and are grouped in the Order Hymenoptera. The larvae are caterpillar-like with eight
pair of fleshy prolegs on the abdomen.
Moth and butterfly caterpillars (Lepidoptera) generally have 5 pair of
prolegs or less. The adult sawfly is
small and looks somewhat like a non-fuzzy bee.
The name sawfly comes from the serrated ovipositor (egg laying structure)
on the adult female. The pine sawflies
insert eggs spaced singly along the length of pine needles. Currently, we are seeing the blackheaded pine
sawfly and the introduced pine sawfly.
The blackheaded pine sawfly has a greenish yellow body with a dark stripe
on each side and green stripes down the back.
The introduced pine sawfly (European origin) also has a shiny black head
but instead of stripes its black body is covered with a variety of yellow to
orange oval shaped markings. The
introduced pine sawfly feeds on eastern white pine. Both of these pine sawflies can defoliate their
hosts. The damage can also be cumulative
when multiple generations occur throughout the summer and even into the
fall. The most damage from the
introduced pine sawfly usually occurs from the last generation that can feed
well into the fall, especially when the killing frost comes late.
Many insecticides labeled for
ornamentals can be used to control sawflies including malathion, diazinon,
Dursban, Orthene, Sevin, Scimitar, Talstar, Tempo, Bayer Advanced Garden
Multi-Insect Killer, Decathlon, Tempo SC Ultra, Conserve SC, SpinTor, Merit,
Marathon, and Bayer Advanced Garden Rose & Flower Insect Killer. The BT insecticide (Dipel and other brands)
will not work on sawflies since it only works on Lepidoptera. Remember to first count prolegs to identify
them as sawflies or not.
Using Bacteriophages to
Control Bacterial Spot and Speck of Tomato
Steve Bost
Several tomato growers are
trying bacteriophage products to control bacterial spot and speck. Bacteriophages (phages) are viruses that
attack bacteria. They are very specific,
attacking only the bacteria that they match. Thus, phages are safe to use and
environmentally friendly. Agriphage
brand, by Omnilytics, Inc., is available under an experimental use permit.
The advantages of phages
include their human and environmental safety, and their moderate effectiveness
against the targeted bacterial plant pathogens, including those that have
become resistant to the primary control product, copper. Phage use relieves the selection pressure on
the bacterial populations caused by excessive copper use.
The disadvantages of phages
are several, with low effectiveness being one.
Two years ago, I conducted a bacterial spot control trial in which
Agriphage provided only about 33% control, versus 96% control by a
copper/mancozeb tank mix. The problem
many growers are facing is copper-resistant bacterial strains, in which case
the phage would outperform copper. Tank mixing the phage with copper might seem
appropriate if you are not sure if your bacterial population is resistant to
copper. However, Agriphage cannot be
tank mixed with copper, because of reduced phage efficacy.
How the program works: Omnilytics will provide you with a suspension of phage
that genetically matches the bacterial population in your field. You need to send them a sample of your
diseased plants so that they can develop the phage strain needed. About 10 days are required for this process,
including shipping time. So that you can
immediately begin spraying preventively with a phage, rather than waiting until
the disease appears, Omnilytics will send you a generic mixture of phages that
are matched against the common strains of your disease. When you receive the specific phage, you use
it on a weekly schedule. If control does
not appear to be satisfactory, you can re-sample and submit for production of a
phage strain better matched to your predominant population. You will not be charged for strain testing;
only for the product. Let me know if you
need contact information for Omnilytics.
Quadris Injury on
Tobacco
Steve
Bost
Twenty-four
counties in Tennessee have received a crisis exemption type of Section 18 label
for the use of Quadris fungicide on dark and burley tobacco for control of
frogeye leaf spot and target spot.
Quadris frequently causes injury on tobacco in the form of enhanced
weather fleck (ozone injury). Typically,
Quadris injury occurs on mid-stalk leaves, but is irregular in
distribution. Not all mid-stalk leaves
will be affected, and the flecks are usually present on only parts of
them. Not all plants contain affected
leaves, and severity varies from plant to plant. Lesion color is not always
white or silver; it can be various shades of brown, from straw-colored to
reddish brown. Lesion shape can be
angular to circular.
Severity
may be increased if Quadris is tank mixed with sucker-control products,
Thiodan, or EC formulations of other insecticides. Broad necrotic areas have been caused with
such tank mixes. Natural conditions that
increase the phytotoxic effects of Quadris include high ambient levels of
atmospheric ozone and probably sulfur dioxide (Ozone and sulfur dioxide can
combine to cause injury to plants before either of these pollutants alone would
cause damage).
Remember: A condition of the special label is that all
users must accept liability for the use of Quadris on tobacco. This was the
only condition under which the manufacturer would agree to support this label.
Velvet Ants - Large,
Fuzzy, Red/Orange and Black Wasps
Karen M. Vail
We started receiving calls
about large, fuzzy “ants” for a few weeks now.
Often folks are concerned that these are fire ants and are amazed when I
explain that velvet ants are wingless wasps. Most are also amazed that they are
found in Tennessee because they have not seen them in the 30 or more years they
have resided here.
Useful questions and answers
that will help identify the mystery “ant” as a velvet ant are listed below:
1. Q: Does it resemble an
ant? A: Yes.
2. Q: Is the insect hairy or
velvety? A: Yes.
3. Q: Does the insect have a
bump on the waist? A: No.
4. Q: Is it orange or red
with black stripes on the abdomen? A: Yes.
5. Q: Is it difficult to
crush? A: Yes.
6. Q: Does it produce a
rasping sound when stepped on? A: Yes.
7. Q: Are there many of these
ants in a trail? A. No.
The velvet ant’s common name
is a misnomer. They are actually more
closely related to wasps than ants and are often called wingless wasps. The wingless females resemble an ant, but
lacks a node or bump on the waist.
Males, on the other hand, do have wings and actively fly. These ants are
orange or red and often have black stripes toward the back of the abdomen. A
dense coating of velvety hair covers this insect. An image of Tennessee velvet ants can be
found at http://web.utk.edu/~extepp/profiles/insects/velvetant.htm .
Biology. Velvet
ants are solitary wasps. Larvae, the immature feeding stage, feed externally on
the prepupal or pupal stages of ground-nesting bees, other wasps and some flies
and beetles. Females actively search for hosts on which to deposit eggs. The
host is attacked after the cocoon has been spun or the fly puparium formed.
Upon locating a host, the female uses its long ovipositor (which can also
function as the stinger) to penetrate the cocoon or puparium and deposits one
or two eggs. Eggs hatch and larvae feed on the host, devouring it. After
feeding, the larval velvet ant spins its own cocoon inside that of its host.
Overwintering occurs as the prepupal stage inside the host's cocoon.
Upon emerging as adults,
winged males search for mates. The male is attracted by a specific sound
produced by a rasping structure located between their second and third
abdominal segments of the female. The rasping sound also occurs when the wasp
is pressed or attempted to be crushed. Mating usually lasts just a few seconds.
Males may also be seen visiting flowers in search of nectar.
Importance. Females spend much time in sandy areas searching for
hosts and may be encountered by adults and children. The females can sting
repeatedly. The stinger is long and produces quite a painful sting --perhaps
the reason that the large common species is called the"cow killer".
People are most often stung by velvet ants while walking in infested areas
without proper footwear. The intensity of pain and allergic reaction to the
sting will vary according to the immune response of the person stung. These are solitary creatures and the
possibility of being stung by a number of these insects at one time is unlikely.
Ground-dwelling bees, which may be important pollinators of some crops, are
known to be hosts for velvet ants. Other species are reportedly pests of white
grub parasites, a condition known as hyperparasitism. Therefore, velvet ants
can be considered either beneficial or pestiferous depending upon the host
species attacked.
Control Measures. Chemical control of velvet ants is rarely needed. The
best methods for dealing with velvet ants are: 1) to inform people, especially
children, not to handle these insects and 2) to wear shoes in infested areas to
avoid accidental encounters. On occasion, the numbers of velvet ants in an area
such as gardens or underneath houses, trailers or other raised structures may
be high enough to warrant control. In these cases, the best control tactic
would be to eliminate ground-nesting wasps or bees on which immature velvet
ants feed. Although the exoskeleton seems uncrushable, individual velvet ants
can be killed by crushing. Household aerosol formulations labeled for wasp
control can also be directed at the velvet ant.
If you are still unsure of
the “ant’s” identification, more information on ant, including fire ant,
identification and management, can be found in our new fire ant web site at:
Imported Fire Ants in
Tennessee
Modified from: Drees, B.
1988.VELVET ANTS. UC-001 Texas
Agricultural Extension Service.
Precautionary Statement
To protect people and the environment, pesticides should be used safely.
This is everyone’s responsibility, especially the user.
Read and follow label directions carefully before you mix, apply, store or dispose of a pesticide.
According to laws regulating pesticides, they must be used only as directed by the label.
Persons who do not obey the law will be subject to penalties
Disclaimer Statement
Pesticides recommended in this publication were registered for the prescribed uses when printed. Pesticide regulations are continuously reviewed.
Should registration or a recommended pesticide be canceled, it would no longer be recommended by
The University of Tennessee.
Use of trade or brand names in this publication is for clarity and information; it does not imply approval of the product to the exclusion of others that may be of similar, suitable composition, nor does it guarantee or warrant the standard of the product.
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COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS
The University of Tennessee Institute of Agriculture, U.S. Department of Agriculture,
and county governments cooperating in furtherance of Acts of May 8 and June 30, 1914.
Agricultural Extension Service Charles L. Norman, Dean