Fruit Pest News
Volume 9, No. 10 May 28 2008
An online newsletter whose goal is to provide all interested persons with timely information on diseases and insects of commercial fruit and vegetable crops in Tennessee.
Text appearing in blue or red can be clicked to link to other web sites. Be aware that much of the linked information is produced in other states and may not be applicable to Tennessee.
In This Issue:
1. First Reports for the Year in TN
2. New Pythium Control for Greenhouse Tomatoes
3. Fire Blight: Managing Affected Trees
4. New List of Organic Disease-Control Products
5. Vegetable Virus Disease Alert
6. Two Spotted Spider Mites and European Red Mites on Peaches
7. Pheromone Trap Catches
1. Sclerotinia stem rot of field tomatoes, May 22, Wilson Co.; Phomopsis cane and leaf spot on Seyval grape and oxidant stipple on Concord grape, May 27, Davidson Co.
2. New Pythium Control for Greenhouse Tomatoes
We have been successful in obtaining a Section 24(c), SLN label for Terramaster 4EC fungicide for control of Pythium and Phytophthora root rot in greenhouse tomatoes. One other fungicide, Previcur Flex, is registered for this use. However, Previcur Flex is not readily available; whereas, Terramaster 4EC is widely used in tobacco and cotton production and can be found wherever these crops are grown. Terramaster is a very effective Pythium fungicide, but you must be careful not to cause plant damage with your application. It cannot be used on seedlings. If you need a fungicide on seedling tomatoes, you must use Previcur Flex.
The method of application of Terramaster on greenhouse tomatoes is through drip irrigation. The following is from the SLN label:
Apply Terramaster 4EC in a 0.01% solution (6.5 fluid oz. in 500 gallons of water) no sooner than 3 weeks after transplanting, using a volume of 6 - 8 fl. oz. per plant. Reapply as needed, but no sooner than 3 weeks after a previous application. Do not exceed 4 applications of Terramaster 4EC per crop. Do not apply within 3 days of harvest. Uniform distribution of Terramaster 4EC through the growing medium is essential for best results. Localized over-dosing may cause crop damage and under-dosing may cause ineffective disease control. Terramaster 4EC should be introduced into the growing medium only after the medium has been thoroughly irrigated to ensure adequate product movement through the growing medium. Continue irrigation until the entire desired quantity of Terramaster 4EC has been introduced. Do not mix Terramaster 4EC with other pesticides or fertilizers unless compatibility tests have shown complete compatibility.
Our thanks go to Chemtura Corporation for their assistance in obtaining this label. (SB)
3. Fire Blight: Managing Affected Trees
Following are some reminders for management of fire blight at this time of year. Efforts to limit secondary spread by cutting out fire blight strikes are most successful if the strikes are removed immediately after they appear. By this time in Tennessee, it is too late for strike removal to effectively reduce the rate of spread of the epidemic. Pruning of fire blight shoots during the growing season should be limited to light to moderate cases. Extensive pruning of heavily blighted trees is neither practical nor desirable, as the result would be the stimulation of new, succulent tissue, which is very susceptible. However, young trees and high density, dwarf-tree orchards should be followed closely and strikes should be removed immediately, regardless of the severity of the outbreak. In such trees, the infection can spread internally to the rootstocks and cause tree death.
Classical recommendations for growing-season removal of fire blight strikes include making the cut 8 to 12 inches below the blighted area and sterilizing the pruning tool between each cut. We now know that this approach has limited effect because of the systemic nature of the bacterial infection. If the infected shoot is associated with the main trunk or a major scaffold limb, you may want to try the "ugly stub" cut, leaving a four-inch stub for winter removal.
Other practices to keep in mind: Excessive tree vigor should be discouraged. Use management systems that promote early cessation of tree growth without adversely affecting tree vigor. Maintain good control of sucking insects, as some of them can transmit the causal bacterium to healthy shoots. If you prune fire-blighted shoots and limbs, remove and destroy them since they can serve as a source of inoculum. If the amount cut cannot be removed quickly, there may be too much blight present for the cutting operation to be effective. (SB)
4. New List of Organic Disease-Control Products
A new fact sheet from Ohio State that provides a list of organic disease-control fungicides can be found at http://ohioline.osu.edu/hyg-fact/3000/pdf/HYG_3310_08.pdf . The authors include a notation by each product indicating whether research has shown the product to be effective.
Also, the Biopesticide and Organic Database that was published last year by IR-4 is very helpful, found at http://www.ir4.rutgers.edu/Biopesticides/LalbelDatabase/index.cfm . You can find all biological products labeled for use on any type of plant. You just choose the type of pest you're interested in -- diseases, insects, weeds, nematodes, or animals. The database provides the list, indicates whether the product is accepted for organic production, and provides a link to the label. (SB)
5. Vegetable Virus Disease Alert
The number of whitefly-transmitted virus diseases of vegetable crops in Florida and other long-growing-season areas continues to mount. The USDA reports that the number of such diseases in Florida cucurbit fields has reached almost epidemic proportions. Three viruses have been discovered on cucurbits in Florida in recent years, and the geminiviruses such as tomato yellow leaf curl have been present on tomato for several years. In addition, one of the cucurbit viruses -- cucurbit leaf crumple virus -- has been discovered on green beans in southwest Florida. All of these viruses are transmitted by the silverleaf whitefly.
What does this mean to you? We are not immune from this threat. (1) Make every effort to keep these viruses out of Tennessee. Purchase and plant only whitefly-free transplants. (2) Be alert to the presence of whiteflies in your fields. When seeking assistance on diagnosis of a problem in your vegetable crop, let the person know if whiteflies are present. It will greatly aid the diagnosis. (3) Do seek assistance if you think your crop has a whitefly-transmitted virus. Our regulatory authorities need to know about it, so that a repeat introduction from outside the state can be prevented next year. (SB)
6. Two Spotted Spider Mites and European Red Mites on Peaches
Peaches are more tolerant
of moderate mite populations than plums, apples, or pears. While twospotted spider
mite is the most common mite problem on peaches in Tennessee, European red mite can
also cause injury. Mites have the ability to build in number very rapidly when conditions
are right, especially as temperatures increase and drier weather takes hold. For
this reason, leaves should be inspected regularly for the presence of mites, webbing,
and the on-set of bronzing. Mites on any tree fruit crop are best controlled when
miticides are applied at the first signs of build-up. The goal is to prevent bronzing
and the associated stress to the tree which can indirectly reduce fruit quality.
There are a number of effective miticides available for fruit tree crops.
On peaches, Apollo 0.42SC (21 day PHI) or Savey 50DF (28 day PHI) are a good choice
for the rare circumstances when heavy mite infestations are found early-to mid-season
that require treatment. The shorter pre-harvest intervals (PHI) of Acramite 50WS
(3 days PHI), Nexter 75 WP and Pyramite 60 WSB (7 days PHI), Envidor 2SC (7 days
PHI), and Vendex 50WP (14 days PHI) on peaches makes these miticides good choices
for any needed curative applications. Note that these miticides have some differences
in their effectiveness depending on the mite. Acramite is especially good against
twospotted spider mites. Nexter and Pyramite are very effective against European
red mites, although at higher rates, these products provide good control of twospotted
spider mites. (FH)
7. Pheromone Trap Catches and Biofixes (FH)
Nashville
(Davidson County) Pheromone Trap Catches for 2008
Oriental fruit moth (OFM), redbanded
leafroller (RBLR), obliquebanded leafroller (OBLR), codling moth (CM), grape berry
moth (GBM), variegated leafroller (VLR), black cutworm (BCW), diamondback moth (DBM),
armyworm (AW)
| OFM | RBLR | OBLR | CM | GBM | VLR | BCW | DBM | AW | CL | |
| 3-10 (Put out RBLR trap) | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| 3-13 | -- | 2* | -- | -- | -- | -- | -- | -- | -- | -- |
| 3-19 | -- | 5 | -- | -- | -- | -- | -- | -- | -- | -- |
| 3-31 | -- | 7 | -- | -- | -- | -- | -- | -- | -- | -- |
| 4-1 (put out BCW, OFM, CM, VLR, OBLR traps) | ||||||||||
| 4-9 | 0 | 2 | 0 | 0 | -- | 0 | 0 | -- | -- | -- |
| 4-11 (put out AW trap) | 2** | 0 | 0 | 0 | -- | 0 | 0 | -- | -- | -- |
| 4-17 (put out GBM, DBM, CL traps) | 0 | 0 | 0 | 0 | -- | 0 | 0 | -- | 0 | -- |
| 4-18 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 4-24 | 2 | 0 | 0 | 0 | 3*** | 0 | 0 | 0 | 0 | 0 |
| 4-29 | 2 | 16 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| 5-12 | 6 | 0 | 3^ | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 5-20 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 5-27 | 1 | 6 | 17 | 0 | 0 | 0 | 0 | 2 | 0 |
0 |
* Biofix for RBLR in Davidson County was March 13.
**Biofix for OFM in Davidson
County was April 11.
***Biofix for GBM in Davidson County was April 24.
^Biofix
for OBLR in Davidson County was May 12.
Bradley County Pheromone Trap Catches
for 2008
tufted apple bud moth (TABM)
| 3-18 (put out OFM trap) | OFM | CM | TABM |
| 4-6 (put out CM trap, TABM) | 0 | -- | -- |
| 4-12 | 0 | 1 | 4 |
| 4-14 | 0 | 0 | 2 |
| 4-19 | 0 | 1 | 0 |
| 4-21 | 0 | 0 | 23 |
| 4-29 | 1 | 5 | 14 |
| 5-5 | 0 | 2 | 5 |
| 5-11 | 0 | 2 | 13 |
| 5-19 | 0 | 1 | 23 |
| 5-26 | 0 | 0 | 8 |
Putnam County Pheromone Trap Catches for 2008
| 3-16 (put out RBLR, OBLR, VLR) | OFM | RBLR | OBLR | CM | VLR |
| 3-21 | -- | 12* | 0 | -- | 0 |
| 4-1 | -- | 5 | 0 | -- | 0 |
| 4-9 (put out OFM, CM) | -- | 7 | 0 | -- | 0 |
| 4-13 | 0 | 0 | 0 | 0 | 0 |
| 4-22 | 0 | 9 | 0 | 0 | 0 |
| 4-29 | 0 | 0 | 0 | 0 | 0 |
| 5-4 | 0 | 0 | 0 | 0 | 0 |
| 5-13 | 0 | 0 | 10** | 0 | 0 |
| 5-20 | 0 | 0 | 30 | 0 | 0 |
*Biofix for RBLR in Putnam County estimated as prior to March 21 (trap not out
early enough).
**Biofix for OBLR in Putnam County was May 7.
Obion County
Pheromone Trap Catches for 2008
| OFM | RBLR | OBLR | CM | VLR | |
| 3-22 (RBLR trap put out) | -- | -- | -- | -- | -- |
| 3-28 | -- | 10* | -- | -- | -- |
| 4-7 (other traps put out) | -- | 0 | -- | -- | -- |
| 4-14 | 0 | 0 | 0 | 0 | 0 |
| 4-21 | 2** | 0 | 0 | 0 | 0 |
| 4-28 | 0 | 0 | 0 | 0 | 0 |
| 5-5 | 1 | 0 | 0 | 0 | 0 |
| 5-12 | 2 | 1 | 0 | 0 | 0 |
| 5-19 | 0 | 0 | 3*** | 1 | 0 |
*Biofix for RBLR in Obion County was March 28
**Biofix
for OFM in Obion County was April 21
***Biofix for OBLR for Obion County was
May 19
The Fruit Pest News URL is: http://web.utk.edu/~extepp/fpn/fpn.htm
Contacts:
Steve Bost, Professor and Extension Plant Pathologist
Frank Hale, Professor and Extension Entomologist
Both authors available at:
615-832-6802
fax 615-781-2568
Soil, Plant and Pest Center
5201 Marchant Drive
Nashville, TN 37211
Copyright 2008 The University of Tennessee. All rights reserved. This document may be reproduced and distributed for nonprofit educational purposes provided that credit is given to University of Tennessee Extension.
Programs in agriculture and natural resources, 4-H youth development, family and consumer sciences, and resource development. University of Tennessee Institute of Agriculture, U.S. Department of Agriculture and county governments cooperating. UT Extension provides equal opportunities in programs and employment.
