“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

http://fireants.utk.edu

 

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