Fruit Pest News
Volume 8, No. 5 April 10, 2007
A weekly, 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. Current Conditions
2. Fruitless Fruit: Suggested Spray Programs for Defruited Plantings
a. Apples
b. Peaches
c. Strawberries
d. Blueberries
e. Blackberries
f. Blueberries
g. Grapes
3. A Special Word About Fire Blight
4. Pheromone Trap Catches and Biofixes
1. Current Conditions
What more can be said about the wild ride in temperatures lately? The fruit situation is not pretty. After several mornings of temperatures that ranged from 20 to 25 F over much of the state, the damage is currently being assessed. It will be some time before it is known just how extensive the damage is to each type of plant. Wood damage has a delayed effect, and much of that won't be apparent until the weather becomes hot and dry this summer, and the tree's conducting system can't provide the leaves with what they need. Fruit losses were extensive. Some of the strawberry crop was saved with freeze protection efforts. I'm glad that those of you who use irrigation for freeze protection are finally getting your rest!
The damage is done, but even where the fruit are gone, we must assume that plant structure is still sound and will produce fruit next year. It is important to maintain at least a minimum spray program where blocks have been frozen out. You don't want to lose many leaves since that can affect fruit bud set for next year and predispose trees to winter injury. This issue will feature low-cost strategies for maintaining pest control during a no-fruit year. (SB)
2. Fruitless Fruit: Suggested Spray Programs for Defruited Plantings
Many growers have experienced a total loss of fruit. Although there will no return on the investment this year, these blocks still require protection from certain types of pests - those that present a threat to the livelihood or future productivity of the plants. Pests that present serious threats of leaf loss or wood damage are the ones on which to focus. But with no income to cover the costs of the applications, economics of the spray program must be a major consideration. The spray programs suggested below are considered minimal programs that should provide adequate protection during a fruit-free growing season. (SB)
2a. Apples - Some late blooms may avoid a total wipeout on the apple crop. In fruit-less blocks, try to minimize diseases that can cause significant leaf loss and insects that threaten the livelihood of the trees.
Control of scale insects should not be overlooked because they can build
up to damaging levels on the branches. First generation crawlers are generally active
from petal fall to third cover and they are known to move to fruit. If populations
are allowed to build this year, they could be a real problem on fruit next year.
Start sampling for crawlers now by making traps with double sided tape wrapped around
a small portion of an infested twig or wrapping the twig with black electrical tape
coated with a thin layer of petroleum jelly. When crawlers are caught in the traps,
treat with an insecticide such as Dimethoate 4EC/400, Diazinon 50WP, Guthion 50WP,
Esteem 0.86EC, Centaur 70WP, Assail 30SG, or a summer horticultural oil.
Dogwood
borer control is very important on apples. Apply insecticides (Lorsban 50W, Lorsban
4E, Thiodan 3EC, Thionex 3EC, Asana XL) with a handgun sprayer to the trunk, especially
to burr knots and graft unions. Moths can lay eggs from April through September.
In Tennessee, a peak moth emergence usually occurs in late April and another peak
occurs in mid-July. Treatment before July is optimal.
Diseases that can cause significant defoliation or leaf injury during the season are scab, cedar-apple rust, Glomerella leaf spot, Alternaria blotch, and necrotic leaf blotch on Golden Delicious. An EBDC fungicide (mancozeb, maneb, Polyram) at 3 lb/acre applied every 10-14 days should provide adequate control of these diseases inexpensively. Up to seven applications can be made at this rate if no fruit are present. If powdery mildew is a threat, add sulfur at 3 - 6 lb/acre, depending on brand. If better control of scab and cedar-apple rust is desired, use Nova plus an EBDC in the springtime sprays. For fire blight control, Dr. Turner Sutton recommends copper at 0.2 - 0.6 lb of metallic copper per acre (e.g., 0.4 - 1.2 lb of Kocide 101). (FH & SB)
2b. Peaches - Peachtree
borers attack the trunks every year so protect the lower scaffolds, vase, trunk and
exposed roots. Insecticide should be applied at the normal post harvest time (July
or so). The preferred application method is to use a handgun applied bark spray.
Chlorpyrifos (Lorsban 4E) is the material of choice. Two sprays of esfenvalerate
(Asana XL) or endosulfan (Thiodan 3EC, Thionex 3EC) may be used instead of the single
spray of chlorpyrifos. Pheromone mating disruption treatments with Isomate-L have
been used with careful monitoring by IPM professionals as a substitute for insecticide.
Lesser
peachtree borer attacks the branches. It is slower to develop but can become a problem.
I spoke to Dr. Dan Horton at the University of Georgia about the management of this
pest for this year. Lesser peachtree borers can be a major pest, especially in middle
and south Georgia. Most growers in that part of Georgia are making two oil sprays
for mites and scale which is much more than has been done in the past. These oil
sprays really help to limit the build-up of European red mites and scale. For growers
who have done a good job with their oil sprays, an airblast spray application with
Asana XL in the next 10 days for lesser peachtree borer is a good strategy. Then,
follow-up with the previously mentioned chlorpyrifos application in July for peachtree
borer.
San Jose scale and white peach scale can be a problem on stone
fruit. Use sticky tape traps to monitor for scale crawlers beginning prior to time
of the 7 to 10 days after shuck split spray. Pyriproxyfen (Esteem 35 WP) should
be applied at crawler emergence. Proper spray timing is very critical for effective
control.
Oriental fruit moth can develop by tunneling into the tips of
the branches during their first generation. It is always important to treat small
nonbearing trees in order to achieve good growth and tree structure.
Some
of the overwintering plum curculio remain in diapause each year. These individuals
will not emerge until next spring to attack the fruit crop. The same thing is known
to occur with codling moth.
Peaches have few diseases that represent a defoliation threat. Varieties that are highly susceptible to bacterial spot may need sprays of Mycoshield or a captan/Syllit tank mix. Even copper could be used, since there are no fruit present. However, reserve this material for the most susceptible varieties to b-spot, because the leaf drop caused by late (post-shuck off) applications of copper could cause more damage than the disease itself. (FH & SB)
2c. Strawberries - Many growers will have a partial crop, and should follow a normal spray schedule, as found in the regional spray guide . Matted row (perennial system) growers who lost their crop may not need any fungicide applications this year unless disease problems develop. Varieties that are very susceptible to common leaf spot or leaf blight may need occasional sprays of captan or thiram. These materials can also be used if anthracnose is known to be present, but be aware that fungicidal control of anthracnose in matted row systems is not very effective. Interference with daughter plant establishment by anthracnose is difficult to control chemically. (SB)
2d. Blueberries - For plantings that have berries, follow a spray schedule appropriate for the site (many blueberry plantings need very little in the way of preventive sprays). For plantings with no berries, fungicide sprays may not be needed. If they are, occasional sprays of captan should be adequate for management of Phomopsis, Anthracnose, and leaf spots. (SB)
2e. Blackberries - For plantings that have berries, follow a spray schedule appropriate for the site. Where no berries are present, captan may be needed if anthracnose has been a problem. Occasional sprays will reduce the amount of anthracnose leaf and cane lesions and reduce the inoculum levels next year. Since rosette inoculum comes only from blossoms, protective sprays for the primocanes would not be needed if there are no living blossoms. However, check nearby wild brambles to make sure their blossoms did not survive the freeze. Where orange rust has been a problem, an application of a rust fungicide such as Nova is needed every two weeks. (SB)
2d. Raspberries - Primocane bearing varieties should have no problem producing a crop, and a normal spray schedule should be followed. Floricane bearing varieties with no crop may need protection against raspberry leaf spot if this defoliating disease has been a problem in the past. Captan or Nova on two-week intervals would be effective. (SB)
2e. Grapes - Most vineyards should have at least some production, on secondary growth. A spray schedule is available here. Even where no berries are present, vines need to be protected against black rot and downy mildew, because of the potential debilitating effect of these diseases. Mancozeb or ziram would be good choices, applied every 10 days in the spring and every 14 days in the summer.
Grape scale is another scale in
which sticky tape traps should be wrapped around the vine to monitor for the crawlers
that should be emerging by May.
Grape root borer pheromone traps are available
to help with the timing of the insecticide spray for this pest. They usually start
emerging in early July. Apply insecticide when these moths are first caught.
Pyrethroid insecticide sprays tend to flare mite infestations. Since
not much insecticide should be applied this year to the foliage, we should have minimal
mite problems. Still, keep an eye on the foliage for signs of mite feeding.
(SB & FH)
3. A Special Word About Fire Blight
Fire blight requires some precaution, as freeze-damage tissue (young leaves and blossoms) can serve as a site of entry by the bacteria. Hopefully, the temperatures during Wednesday's rain will be too cool for infection. Warm weather on Thursday and Friday will reactivate the bacterial population. The hope is that freeze-injured tissues will have healed sufficiently to prevent significant infection during the rain forecast for Saturday. However, a spray on Thursday or Friday might be smart. Where no fruit exist, there should be no harm in using a low rate of copper (0.2 - 0.6 lb/acre of metallic copper). Copper should help reduce the resident population of fire blight bacteria on the surfaces. Streptomycin is not very effective against shoot infections. (SB)
4. Pheromone
Trap Catches and Biofixes (FH)
Nashville (Davidson County) Pheromone Trap
Catches for 2007
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 | |
| 2-22 (caught one RBLR in last year's trap) put out new trap | -- | 1 | -- | -- | -- | -- | -- | -- | -- |
| 2-26 | -- | 0 | -- | -- | -- | -- | -- | -- | -- |
| 2-28 | -- | 1* | -- | -- | -- | 1 | -- | -- | -- |
| 3-2 | -- | 3 | -- | -- | -- | 0 | -- | -- | -- |
| 3-12 | -- | 50 | 0 | -- | -- | 0 | -- | -- | -- |
| 3-14 (Put out OFM, CM, OBLR, BCW) | -- | 26 | -- | -- | -- | 0 | -- | -- | -- |
| 3-20 | 0 | 33 | 0 | 0 | -- | 0 | 0 | -- | -- |
| 3-21 | 1 | 7 | 0 | -- | -- | 0 | 0 | -- | -- |
| 3-26 | 20** | 34 | 0 | -- | -- | 0 | 0 | -- | -- |
| 3-27 (put out AW trap) | 8 | 4 | 0 | 0 | -- | 0 | 0 | -- | -- |
| 3-30 | 12 | 16 | 0 | 0 | -- | 0 | 0 | -- | 0 |
| 4-2 | 18 | 18 | 0 | 0 | -- | 0 | 0 | -- | 1 |
| 4-3 (put out DBM, GBM) | 10 | 1 | 0 | 0 | -- | 0 | 0 | -- | 0 |
| 4-5 | 11 | 0 | 0 | 0 | 4*** | 0 | 0 | 0 | 0 |
| 4-10 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
* Biofix for RBLR in Davidson County was February 28.
**Biofix for OFM in Davidson
County was March 26.
***Biofix for GBM in Davidson County was April 10.
Bradley County Pheromone Trap Catches for 2007
| OFM | CM | |
| 3-26 | 1 | 0 |
Putnam County Pheromone trap Catches for 2007
| OFM | RBLR | OBLR | CM | VLR | |
| 3-19 | 1 | 9* | 0 | 4*** | 0 |
| 3-21 | 1** | 3 | 0 | 2 | 0 |
| 3-23 | 2 | 6 | 0 | 1 | 0 |
| 3-26 | 2 | 15 | 0 | 2 | 0 |
| 3-28 | 4 | 7 | 0 | 1 | 0 |
| 3-30 | 2 | 14 | 0 | 0 | 1 |
| 4-2 | 6 | 32 | 0 | 0 | 0 |
| 4-6 | 2 | 28 | 1 | 1 | 0 |
*Biofix for RBLR in Putnam County estimated as March 2 (trap not out early enough).
**Biofix
for OFM in Putnam County March 21.
***Waiting to verify biofix for CM, many unknown
moths being caught in these traps that can easily be mistaken for CM..
Obion
County Pheromone Trap Catches for 2007
| OFM | RBLR | OBLR | CM | VLR | |
| 3-19 | 0 | 17* | 0 | 0 | 0 |
| 3-26 | 5** | 89 | 0 | 1 | 0 |
*Biofix for RBLR in Obion County estimated to be on March 2 (trap not out early
enough).
**Biofix for OFM in Obion County on March 26.
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
Plant and Pest Diagnostic Center
5201 Marchant Drive
Nashville, TN 37211
Copyright 2007 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.
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