IPM NEWSLETTER Update for Field Crops and Their Pests

Transcription

1 Agricultural Extension Service The University of Tennessee IPM NEWSLETTER Update for Field Crops and Their Pests 605 Airways Boulevard Jackson, TN No. 7 June 13, 2003 Past Newsletters: Cotton Current Crop Condition (Chism Craig, Assistant Professor) Cotton has responded well to the recent sunshine but more is still needed. We have a tremendous variety of cotton growth stages throughout the state. Cotton planted during the last two weeks of April is beginning to look like cotton, while cotton planted during the first and second weeks of May is just starting to grow. Late May planted cotton is beginning to grow and should really take off as we accumulate some heat. The cool wet weather has been excellent for weed growth and also excellent for weed control. Weed control with preemergence and foliar applications has been excellent when used. I have seen some herbicide injured plants which can be expected when foliar applications are made during cool, cloudy conditions or when the humidity is high and the ground saturated. Cotton should grow out of this injury if growing conditions improve. Sheltered, early-planted cotton is most likely beginning to square, and mepiquat chloride applications will be needed in the next few weeks. I m not ready to pull the trigger on a lot of this cotton because I still believe that we need to achieve some more growth. Heat unit accumulation has been below normal and much of this cotton is still behind. Isolated areas have some cotton in need of applications and if we receive good sunshine and heat, most early planted cotton will need an application after match-head square. Most cotton 6 inches tall and less is receiving some sort of over-the-top glyphosate application, however, post directed and hooded applications will be needed to keep weeds in check. The following is from the Weed Control Manual for Tennessee. It contains information regarding post-directed and hooded applications. It is also on-line at: Proper calibration of post-directed and hooded applications is essential for good control and minimal crop injury. A guide to proper calibration can be found at the following link: Post-directed glyphosate applications: Sprays must be directed to the base of the cotton plant. Take care to minimize contact of the spray with cotton leave by placing nozzles in a low position directing a horizontal spray pattern under the cotton leaves and by using low pressure (less than 30 psi). Leaf contact may result in boll loss, delayed maturity and/or yield loss. Two directed applications, at least 10 days apart and with at least two additional nodes developed following the first application, may be made. Do not exceed 32 ozs./a (3ae), 26 ozs./a (3.7ae) or 22 ozs./a (4.5ae) per application. A total of 4 qt./a (3ae), 3.2 qt./a (3.7ae) or 2.5 qt./a (4.5ae) may be applied from cracking to layby. 1

2 Herbicide For Cotton at Least 6" Tall Caparol/Cotton-Pro 4L (Prometryn) + MSMA Cobra (Lactofen) + Crop Oil Concentrate Direx 4L or Direx/Karmex 80 DF (Diuron) Goal 2XL (Oxyfluorfen) For Cotton at Least 8" Tall Linex 4L (Linuron) Rate/Acre Broadcast* Active Ingredient Formulation lb lb lb lb lb pts oz pt pt. 4L or DF 1-2 pts pts. 4L Remarks Apply as a directed spray when cotton is at least 6" tall. If omitting MSMA, be sure to add surfactant (2 qts./100 gals. of spray mix). Caparol can be applied, at a reduced rate, to 3 to 6" cotton. See label. Apply as a directed spray when cotton is at least 6" tall. Do not allow spray to contact cotton leaves or crop injury will result. Apply as a directed spray when cotton is at least 6" tall. Lower rate is for pigweed under 2" tall only. If omitting MSMA, be sure to add surfactant (1 qt./100 gals. of spray mix). Apply as a directed spray when cotton is at least 6" tall. Do not allow spray to contact cotton leaves or crop injury will result. If target weeds have more than 3 true leaves, use the higher rate of Goal. If omitting MSMA, be sure to add surfactant (1-2 qts./100 gals. of spray mix). State label for Tennessee. Apply as a directed spray when cotton is at least 8" tall and when weeds are not over 2" tall. If applying Linex 4L alone, add a nonionic surfactant at the rate of 2 qt. per 100 gal. of spray mix. For Cotton at Least 12" Tall Aim 2EC (Carfentrazone-ethyl) lb ozs. Aim is a contact herbicide for postemergence directed spray control of broadleaf weeds. Apply Aim alone or tank mixed with other herbicides to emerged and actively growing weeds. Applications to cotton with less than 5 to 6 nodes must be made with hooded sprayers to completely avoid contact with the cotton plant. Layby applications of Aim or Aim tank mixtures at later growth stages may be made when cotton plants have achieved a height of 12 inches or more with sufficient bark development and height differential between crop and bottom leaves. Directed sprays should position nozzles a minimum of 3-4 inches above the soil with nozzles directed underneath the cotton canopy. Spray solution should be directed at the base of cotton plants for minimum contact with green stems and foliage while maintaining maximum contact with weeds. For best performance, make applications to actively growing weeds up to 4 inches tall. Coverage is essential for good control. Use a crop oil concentrate at 1% v/v (1 gallon per 100 gallons of spray solution). Hooded Applications Herbicide Aim 2EC (Carfentrazoneethyl) Gramoxone Max (u) (Paraquat) Rate/Acre Broadcast* Remarks Active Formulation Ingredient ozs. Aim is a contact herbicide for postemergence control of broadleaf weeds. Apply Aim with a lb. hooded sprayer alone or tank mixed with other herbicides to emerged and actively growing weeds. Applications to cotton with less than 5 to 6 nodes must be made with hooded sprayers to completely avoid contact with the cotton plant. For best performance, make applications to actively growing weeds up to 4 inches tall. Coverage is essential for good control. Use a crop oil lb. concentrate at 1% v/v (1 gallon per 100 gallons of spray solution) ozs. State label for Tennessee. Apply in cotton at least 6" tall using hooded sprayers only. Avoid crop contact. Always add nonionic surfactant (1 qt./100gals.of spray mix). Operate hoods as close to soil surface as possible. Gramoxone Max is labeled for tank-mix applications with residual herbicides (Cotoran, Caparol/Cotton-Pro, Direx/Karmex). See labels for rates and precautions. Touchdown/others* lbs ozs. Apply in cotton at least 6" tall using hooded sprayers only. Avoid crop contact. Operate (Glyphosate 3ae) (a.e.) hoods as close to soil surface as possible. Roundup UltraMax* ozs. (Glyphosate 3.7ae) Roundup WeatherMax* (Glyphosate 4.5ae) ozs. Rates are expressed on a broadcast basis. Use the conversion table, later in this section, to determine band rates. 2

3 Factors to convert Broadcast Rate/A to a Band Rate at Various Row and Band Widths. Band Width(in.) Row Width (in.) To Convert: Find the factor for your combination of row width and band width and multiply the broadcast rate by this number. Example: A producer plans to apply 0.5 lb. (broadcast rate) per acre of Direx 80 DF on a 12 in. band on 38 in. rows. Multiply 0.31 by 0.5 lb. to get 0.16 lb./a on a 12 in. band. Figure 1. Illustration of proper post-directed application (PB 1532 Weed Control Guidelines for Mississippi) Figure 2. Diagram illustrating 1 and 3 nozzles per row in hooded sprayers (PB 1532 Weed Control Guidelines for Mississippi) DD-60 Accumulation (TASS and NWS data) Location 4/13/03 6/1/03 5/4/03 6/1/03 Ames Plantation Brownsville Covington Dyersburg Jackson Memphis Milan Cotton Insects, Etc. (Scott Stewart, Associate Professor) Trapping: Moth and boll weevil trap catches are appended to the end of this report. You will note much of the same pattern in boll weevil catches as last year (i.e., most weevils being caught in counties bordering the Mississippi River). 3

4 Slugs are the big, continuing problem of the last week. They have caused near complete stand loss in isolated fields of no-till cotton. These fields will likely be replanted to soybeans. The slugs will still be there, but the soybeans may outgrow the problem. Tillage, if an option, should be considered in heavily infested fields before replanting. The current problem is clearly associated with heavy debris and seems to be most severe in fields rotated from corn. Slug damage is clearly greater problems in low areas of fields. The greatest damage seems to be in fields, or parts of fields, where the furrow did not completely close because of wet conditions at planting. However, these tend to be low, wet fields to begin with. Slugs may be seen early in the morning, especially cool and cloudy days, but once the sunshine hits, they head for cover. Reflective slug trails can sometimes be seen on plants with the help of the morning sun. Slugs feed primarily at night. During midday, I ve found slugs buried 1-inch deep, under plant debris, in the middles of rows. I ve heard reports that Larvin and Lorsban appear to be giving some control, but we need to be careful. It is easy to not find slugs, and assume they are dead, if you look during the wrong time of the day. In my test last week, Lorsban (1.0 lb ai/acre) provided little control. Larvin may be a good, next choice, but the rates probably need to stay in the range of lb ai/acre. Larvin is used successfully in slug baits in Europe. Most experts suggest spraying late in the day or even at night to get the best control. The only bait I know of that is labeled for cotton is Deadline MP, containing 4% metaldehyde. The problem: the bait needs to be ordered because it is not locally available in field-sized packets, and it cost about $15-17 an acre for the minimum, 10 lb/acre rate. According to the slug expert (Dr. Ron Hammond, Ohio State), this rate normally provides adequate control. Of course, the only threshold I can give you is to treat (and hope for the best) when slug populations threaten to reduce stands below acceptable levels. The good news: the severity of the problem appears to be lessening as growing conditions improve. Craig Massey has put in some reminders and comments about plant bugs and aphids later in this newsletter, so I won t waist a lot of space here. However, let me make some comments about switching chemistries. This is a good idea in terms of resistance management and may be beneficial to the pocket book. For example, you may consider starting with Bidrin, Orthene, or another of the older products for early plant bug control. If aphids and plant bugs subsequently begin to build, the relatively new neonicotinoid insecticides (e.g., Centric and Trimax) may be a good choice. These should provide control of plant bugs and aphids when used at recommended rates. Let me caution you that all insecticides appear to give good control of pests that were absentto begin with. Automatic, pinhead square sprays are no longer recommended because of the absence of boll weevils. Wherever possible, growers should be encouraged to use established thresholds when making insect management decisions. We must not forget thrips because much of the cotton is late planted and less than two nodes. Although the warming weather is a help, we will still need to treat fields that are 3-4 th node or less if they average one or more thrips per plant. Area Cotton Report (6/11/03) - including Dyer, Lake, Gibson, Lauderdale, Obion, Weakley, and Crockett Counties by Hayden E. (Gene) Miles, Area Specialist (IPM) The cotton crop seems to have made some progress in growth this week but is still late compared to previous years. Cotton growth stages range from the cotyledon stage to the 10th node. The earlier planted or older cotton is squaring on the 5th to 7th node with most occurring on the 6th node. Slugs 4

5 are still being noted this week in cotyledon (growth stage) cotton in no-till fields. These pests are being found primarily in cotton rows where the seed furrow was left open. Thrips numbers range up to 4 per plant for the week. Generally light aphid infestation have been reported. Square retentions being reported are 95 percent and above. No plant bug infestations have been reported. Beneficial counts are up to 1.4 per 6 row feet. Area Cotton Report (6/11/03) including Haywood, Shelby, Hardeman, Fayette, Tipton, Madison, and Crockett Counties by Craig Massey, Area Specialist (Plant and Pest Management) Cotton has shown improved growth during the last two weeks and is looking good because of the warmer weather. Cotton is now developing a deeper tap root, and this will be helpful later in the season when cotton is maintaining additional boll loads. Much of the cotton acreage is starting to fruit well, and some earlier planted cotton will be blooming within the next 2 to 3 weeks if good conditions continue. The primary fruit are being set in some fields, and this is a critical time to make sure fields are closely monitored for all insect pests that can endanger the crop. Plant bugs continue to be seen in low to medium numbers, depending on location. Plant bugs are a threat to cotton as small squares from the node. Closely watch nodes 7-14 to maintain square retention at 80% or higher. Cotton should be watched for plant bugs migrating into fields from other host crops and ditch banks. This week plant bugs are averaging 1% to 8% in 100 sweeps. If you are not able to pick up any plant bugs nymphs while scouting with a sweep net, switch over to using a drop cloth and check by beating the cotton plants against the cloth. Small plant bug nymphs look similar to aphids but have longer antennae and move much faster. A large nymph can do the same amount of damage as an adult. Aphids are starting to show up in cotton from low to low medium range. This is about the same as last year. Aphids can be a serious threat to cotton during this critical time of fruit set. Aphids will secrete honeydew that will get on the leaves and cause a fungus to grow creating a sooty appearance to the leaf. Leaves will also begin to curl under along the edges as aphid pressure increases. Treat when these symptoms occur, especially if there are few natural control agents present (beneficials and aphid fungus). PGR Applications: Cotton has really begun to grow because of warm, humid weather and this last rain. It is at this time during the growing season that a plant growth regulator needs to be considered. Applications can be made according to internode length and height to node ratios. Much of the cotton is 7-16 inches and has 5-10 nodes. Webworms have been on the rise in cotton for the past few weeks in non-bollgard cotton. Webworms have a clear body with a black head when they are small. They tend to make a web around themselves when they are smaller and have a distinct radical movement when touched. Do not confuse a bollworm or tobacco budworm with the webworm. The webworm causes minimal damage on most cotton fields. Confusing it with the more serious worm pests may cause some unnecessary treatment. 5

6 Tennessee Pheromone Moth Trapping Summary (Week 1, Ending 6/9/03) Number moths Trap location TBW CEW BAW Madison (South) Madison (North) Hardeman (Bolivar) Fayette (Summerville) Fayette (Oakland) Haywood (Brownville) Haywood (West) Tipton (Avreet) Tipton (Mt. Carmel) Lauderdale (19 W) Crockett (Maury City) Crockett (Alamo) Carroll (Atwood) Gibson (Milan) Gibson (Kenton) Dyer (Dyersburg) Dyer (Newbern) Lake (Ridgley) Tennessee Boll Weevil Eradication - Trapping Summary Cycle 7: through May 29, 2003 (Submitted by Ron Seward, Program Manager) Work Weevils Traps Weevils Weevils Zero % Zero unit Fields Acres caught run per acre per trap fields fields Somerville % Brighton % Brownsville % Alamo % Dyersburg % TOTAL % Total Weevils Trapped Year to Date: 2,204 (vs. 20,080 in 2002) Acres Treated this Cycle: 0 6

7 Boll Weevil Eradication Lake 20 / 9 Obion Weakley Henry Dyer 67 / 10 Gibson Carroll 2 / / 14 7 / 0.20 Lauderdale Crockett Henderson 20 / 0.87 Madison 0 Haywood Tipton 3 / / 67 0 Chester0 Chester 493 / 85 6 / Shelby Fayette Hardeman McNairy Hardin Number of boll weevils trapped by county / Number of weevils per 1000 traps Cycle 07, May 22 28, 2003 Madison C DISCLAIMER STATEMENT Pesticides recommended herein were registered for the prescribed uses when this publication was printed. Should registration be canceled, the University of Tennessee will immediately discontinue its recommendation of the pesticide. 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. The Agricultural Extension Service offers its programs to all eligible persons regardless of race, color. National origin, sex religion, disability or veteran status and is an Equal Opportunity Employer. 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, Agricultural Extension Service, Charles L. Norman, Dean. Scott D. Stewart (editor) Extension Cotton IPM Specialist 7