Fruit Pest News
Volume 3, No. 1 March 11, 2002
A weekly, online newsletter whose goal is to update Extension agents and growers of commercial tree fruit and small fruit crops
on diseases and insects 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.
Welcome! to the first issue of the third volume of Fruit Pest News. We hope the newsletter is helpful to you, so please let us know of any changes we can make to better meet your needs. One of our most important functions is to keep you apprised of pest occurrences in the state. So please let us know when you see a disease or insect for the first time for the year, or if you have an unusual outbreak. We won't use your name. Our contact numbers are at the end of each issue of the newsletter.
Fruit Pest News also brings you research reports, pesticide registration changes, and other pest-related news. The newsletter will be compiled each Monday and should be available for viewing on the Internet the following day. There will be a new issue each week through mid-July, then every two weeks through early October.
In This Issue:
1. Crop Development Stages
2. Blackberries: Prepare for Production Without Benlate
3. Strawberries: Two New Fungicide Registrations
4. Blueberries: Abound Fungicide Registered
5. Tree Fruit: Dormant Oil Sprays
6. Tree Fruit: Insecticide Recommendation Changes for 2002
7. Strawberries: Field Sanitation for Gray Mold Management
1. Crop Development Stages
Fruit crop development is much behind that of the last two years. The mild winter caused some rapid development of buds until the cold weather of the past two weeks. At the Plant and Pest Diagnostic Center at Nashville, the earliest blueberry cultivar in the planting, O'Neal, began to bloom February 20. Temperatures in the low-teens put a stop to that. Apples are at silver tip and Redhaven peach trees are at the red calyx stage of swollen bud. Plasticulture strawberry plants began to bloom in the warm weather of February. Matted row plant buds should still be safely tucked away. Blackberries are at 1/4 to 1/2 inch green tip.
2. Prepare for Blackberry Production Without Benlate
As you probably know, Benlate fungicide has been discontinued by the manufacturer. You can still use it if you can find it. Blackberry growers should make an attempt to locate some Benlate. There are no adequate anthracnose control products registered for blackberries at this time. There are some materials coming down the pipeline but, for this year, suitable anthracnose materials will not be available. What to do if you have anthracnose-susceptible cultivars and do not have any Benlate: Use liquid lime-sulfur at 1/4 to 1/2-inch green tip stage of growth (now). This will not provide an adequate level of control of anthracnose by itself, but it will reduce initial inoculum. If you use lime sulfur, it is important that this operation be done now, as this material can burn leaves if applied later. Then, use a fixed copper at two-week intervals according to the label. Avoid mixing insecticides with copper, especially in hot weather, as phytotoxicity can occur.
Benlate is also used on blackberries for control of rosette disease. However, a suitable alternative is available in the form of copper. Extensive research conducted by Barbara Smith, USDA-ARS in Poplarville, MS, indicates that copper is as effective as Benlate for control of rosette. As always, don't try to rely entirely on chemicals for control of rosette disease. Timely removal of rosettes is key. (SB)
3. Two New Fungicide Registrations for Strawberries
Switch 62.5WG and Quadris 2SC fungicides have been granted federal registrations for strawberries. The registration for Switch occurred last fall and was reported in this newsletter. Although Botrytis gray mold is the only disease on the current label, Switch is very effective against strawberry anthracnose, according to my trials. Novartis is working towards adding anthracnose to the Switch label. Switch has been added to our 2002 recommendations. Remember that you cannot plant anything other than strawberries or onions for 12 months following the last application of Switch. This restriction may eventually be relaxed as Novartis obtains more residue data.
We have had Section 18, emergency-use labels for Quadris for the last three years, for control of anthracnose. The federal label also lists powdery mildew. The federal label was granted after the print version of our 2002 small fruit recommendations went to press, so Quadris is not included there. It is included, however, in the web version of the recommendations. The rate is 6.2 to 15.4 fl oz/acre, with a 0-day preharvest interval. Quadris should be used preventatively, up to 4 applications per year, but not more than twice consecutively.
4. Abound Registered for Several Berries
Abound 2SC fungicide has received federal registrations for blueberry, currant, elderberry, gooseberry, huckleberry, lingonberry, and juneberry. The active ingredient in Abound is azoxystrobin, identical to Quadris. Note that the manufacturer, Novartis, chose to market azoxystrobin for strawberries under the name Quadris, and for blueberries as Abound.
For the bushberries, the target diseases for Abound are mummyberry, Alternaria fruit rot, Phomopsis twig blight, and anthracnose fruit rot. The rate is 6.2 to 15.4 fl oz/acre, with a 0-day preharvest interval. Abound should be used preventatively, up to 3 applications per year, but not more than twice consecutively.
5. Dormant Oil Sprays
If anything, dormant oil sprays are more important now
than ever. Dormant oil sprays help prevent problems down the road. On peaches,
oil helps control San Jose scale and white peach scale as a Dormant or Delayed Dormant
spray. At Dormant, two applications at 10-14 day intervals works best. At Delayed
Dormant to 1-5% bud swell, Lorsban 4E can be added to strengthen performance against
scale crawlers and suppression of lesser peachtree borer on peaches. Do not use
oil after 5% bud swell.
European red mite eggs and San Jose scale are controlled
on apples at Green Tip to 1/2 Inch Green. The use of one of the recommended insecticides
with oil will help control scales and climbing cutworms. Esteem will control San
Jose scale if applied before 1/2 Inch Green. If you are having scale problems, avoid
using pyrethroid insecticides during the growing season, because they can kill scale
predators and parasitoids that normally would help manage scale populations. There
are new insecticides and miticides available for tree fruit, but if you can manage
a pest using the less expensive dormant oil, then it behooves you to get all you
can out of the oil sprays. (FH)
6. Insecticide Changes Made for the 2002
Integrated Orchard Management Guide for Commercial Apples in the Southeast
At
Green Tip to 1/2 Inch Green, it is stated that Esteem will result in poor rosy apple
aphid control. Esteem has thus been removed as an option in the recommendations
for rosy apple aphid. Actara has been added to the recommendations for this pest.
Actara also recommended for plant bug control at Tight Cluster to Pink. At Petal
Fall, Actara is recommended for control of plum curculio, white apple leafhopper,
spotted tentiform leafminer (STLM), and rosy apple aphid. Danitol has been deleted
as an option for rosy apple aphid control at Petal Fall. At Second Cover, include
Actara for control of leafhoppers, STLM, and green apple aphid. Include Lorsban
as a directed trunk spray for dogwood borer at Second Cover. Also at Second Cover,
include Intrepid as an option for Oriental fruit moth (OFM) control and Isomate Rosso
for OFM mating disruption.
A cautionary note was made in the 2002 Southern
Peach, Nectarine and Plum Pest Management Culture Guide. It was stated to not use
Thiodan more than one time as a Petal Fall or Cover Spray due to the potential for
substandard control of plum curculio.
Also, 28 crop uses are being canceled
by the EPA for azinphos-methyl (Guthion, Sniper). Originally that included nectarines,
plums, prunes and potatoes. Now, after negotiation and review, it is expected that
nectarines, plums, prunes and potatoes will no longer be considered ineligible for
reregistration. Crop uses for seven crops (peaches, tart cherries, almonds, cotton,
cranberries, pistachios and walnuts) are being phased out in 4 years. Other crops,
including apples/crabapples, blueberries, sweet cherries, pears, cane berries, pine
seed orchards, brussels sprouts and nurseries for quarantine requirements have been
given four year limited registrations. Prior to the expiration of the 4 year period,
the EPA will review these uses to determine if they should allow registration to
continue.
There has been a voluntary cancellation of phosmet (Imidan) use
on household fruit trees, household ornamentals and domestic pets. Nine crops (apples,
apricots, blueberries, crabapples, grapes, nectarines, peaches, pear, and plum/dried
plums) are authorized for use under specific terms for five years. The reentry interval
(REI) has increased on tree fruit from one day to three days. (FH)
7. Strawberry Field Sanitation for Gray Mold Management
Many plasticulture strawberry producers remove senescent (dead and dying) leaves and stems from their plants before first bloom in the spring. This practice (leaf sanitation) eliminates a food base for the Botrytis fungus and, thus, reduces the amount of spores available for infecting the blossoms. If you have not already done this, it is probably too late, because most fields have begun to bloom, and leaf sanitation would damage the blooms. Furthermore, recent research has cast some doubt on the need for leaf sanitation.
See next week's issue of Fruit Pest News for guidance on designing a fungicide spray program for strawberries. (SB)
The Fruit Pest News URL is: http://web.utk.edu/~extepp/fpn/fpn.htm
Contacts:
Steve Bost, Professor and Extension Plant Pathologist
Frank Hale, Associate 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