Pest & Crop

Newsletter


Purdue Cooperative Extension Service

IN THIS ISSUE

Issue 5, April 28, 2017 • USDA-NIFA Extension IPM Grant




Insects, Mites, and Nematodes

Plant Diseases

Weather Update



INSECTS, MITES, & NEMATODES




Sampling for Plant Parasitic Nematodes: Your Result is as Good as the Sample You Provide (Jamal Faghihi and Virginia Ferris) -



Plant parasitic nematodes are microscopic worm-like organisms that require water to survive and are sensitive to high temperature. Only living nematodes can be extracted from roots. Through the years we have had many samples submitted to the Purdue Nematology Laboratory with little consistency in the quality of the samples. We have discussed proper sampling procedures at every opportunity but not exclusively until now. Sampling might appear trivial but we believe proper sampling is the most crucial step for correct diagnosis. Because we continue to receive improper samples we address this issue again via this article. Even though procedures for sampling among the most important plant parasitic nematodes are similar, there are differences based on the host and the type of nematodes we are trying to recover.

Corn parasitic nematodes: There are three major groups of nematodes that parasitize corn.

  1. Endo-parasites (e.g., Lesion nematodes): These nematodes mostly feed within corn roots. Plant roots along with surrounding soil must be submitted to recover these types of nematodes. A proper soil sample consists of about one quart of sub-samples taken to a depth of 6-8 inches directly from the root zone of affected corn plants Dig up the stunted plants and place with adhering soil and roots in a plastic bag. Attach a label to the outside of the bag. On the label, give sufficient information to identify the sample. Root and soil samples should not become dry or be exposed to high temperature. The best time to sample for these nematodes is mid-season when most of the nematodes have migrated to the inside of the roots. These nematodes continue to feed throughout the growing season. They can be found in all kinds of soil types.
  2. Ecto-parasites (e.g., Needle nematodes): These types of nematodes feed from outside of the young roots. The sampling procedure is the same as described above for Lesion nematodes. But, Needle nematode is mostly a problem in sandy soil and can be found early in the season (4-6 weeks after germination). Often they disappear when the soil temperature rises above 80 degrees.
  3. Semi endo-parasites (e.g., Lance nematode): These nematodes can feed from inside or outside of the roots. The sampling procedure is the same as that described above for endo-parasites. Lance nematodes feed throughout the season, have no soil type preference and can parasitize corn or soybean.

Soybean parasitic nematodes: Lesion and Lance nematodes parasitize soybean too but Needle nematode does not. The sampling procedure for these nematodes in soybean is similar to the one described for corn. The most economically important nematode affecting soybean is the Soybean Cyst Nematode (SCN). The SCN distribution, as for most of the plant parasitic nematodes, is in patches. So it is very important to take many sub-samples to increase possibility of hitting the concentrated areas. A soil probe or a small trowel should be used to collect the sub-samples. Most of these nematodes are within 6-8 inches of the soil. One sample for every 10 acres is ideal. A quart of soil is sufficient and no root samples are required for SCN. Samples can be taken anytime.

 

 

Recommended Optimum Sampling Type and Time for Major Plant Parasitic Nematodes in Indiana.
Host Target Nematode Sample Type Optimum Time to Sample

Corn

Needle

Soil and roots

June-mid July

Corn

Lesion, Lance

Soil and roots

Late June-Late August

Soybean

Lesion, Lance

Soil and roots

Late June-Late August

Soybean

SCN

Soil

Anytime

Turf

All

Soil and roots

June and September

Melons

Root knot

Roots

At harvest

Mint

Lesion

Roots and soil

Late June-September

Mint

Needle

Roots and soil

Late Spring or early fall

Mint

Root knot

Roots

Fall

 

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Alfalfa Weevil Development Map



total precipitation

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Armyworm Pheromone Trap Report



County/Cooperator Wk 1 Wk 2 Wk 3 Wk 4 Wk 5 Wk 6 Wk 7 Wk 8 Wk 9 Wk 10 Wk 11 Wk 12
Dubois/SIPAC Ag Center 0 0 0 101 193 16            
Jennings/SEPAC Ag Center 0 1 1 56 57 9            
Knox/SWPAC Ag Center 0 13 26 42 189 57            
LaPorte/Pinney Ag Center 0 0 3 352 936 382            
Lawrence/Feldun Ag Center 4 108 216 246 650 348            
Randolph/Davis Ag Center 0 29 41 528 1232 300            
Tippecanoe/Meigs 0 2 15 107 730 243            
Whitley/NEPAC Ag Center 0 34 90 537 1689 1349            

Wk 1 = 3/16/17 - 3/22/17; Wk 2 = 3/23/17 - 3/29/17; Wk 3 - 3/30/17 - 4/5/17; Wk 4 - 4/7/18 - 4/12/17; Wk 5 - 4/13/17 - 4/19/17

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Black Cutworm Adult Pheromone Trap Report



County Cooperator BCW Trapped

Week 1
3/23/17-3/29/17

Week 2
3/30/17-4/5/17
Week 3 4/5/17-4/12/17 Week 5 - 4/13/17 - 4/19/17 Week 6 - 4/20/17-4/26/17
Adams Kaminsky/New Era Ag     13 35  
Adams Roe/Mercer Landmark 11 17* 7 42 28*
Allen Anderson/Syngenta Seed   0      
Allen Gynn/Southwind Farms 2 1 0 15 21*
Allen Kneubuhler/G&K Concepts - Trap 1   0 19* 36 60*
Allen Kneubuhler/G&K Concepts - Trap 2   9 2   0
Bartholomew Bush/Pioneer Hybrids 1 13* 13 17 28*
Clay Bower/Ceres Solutions - Clay City 0 0 7 4 2
Clay Bower/Ceres Solutions - Bowling Green 0 0 0   1
Clay Bower/Ceres Solutions - Brazil 0 0 0   0
Clinton Emanuel/Boone Co. CES 8 9 6 10 5
DeKalb Hoffman/ATA Solutions 0 0 0 1 0
Dubois Eck/Purdue CES 14 28* 41* 4 4
Elkhart Kauffman/Crop Tech Inc. 0 0 6 16 28*
Fayette Schelle/Falmouth Farm Supply Inc. 5 33* 5   3
Fountain Mroczkiewicz/Syngenta 7 18* 31* 93* 43*
Fulton Jenkins/N. Central Coop - Talma 0 5 10 13 6
Fulton Ranstead/NCC Coop - Rochester 0 0 0 3 6
Gibson Schmitz/Gibson Co. CES       0 0
Hamilton Campbell/Beck's Hybrids 14 13 18 55*

30*

Hamilton Truster/Reynolds Farm Equipment   1   1  
Hendricks Nicholson/Nicholson Consulting 0 3 4 11 17*
Jasper Overstreet/Jasper Purdue CES 2 5 0 5 10
Jasper Ritter/Brodbeck Seeds 1 3 10 32 28*
Jay Boyer/Davis PAC   3 14 19 19
Jay Shrack/Ran-Del Agri Services 1 3 5 9 8
Jay Temple/Jay County CES          
Jennings Bauerle/SEPAC 0 0 0 0 0
Knox Bower/Ceres Solutions - Freelandville 0 0 0 13* 4
Knox Bower/Ceres Solutions - Vincennes 0 0 0   2
Kosciusko Klotz/Etna Green 0 0 4 9 5
Lake Kleine/Kleine Farms 4 16* 60* 83* 90*
Lake Moyer/Dekalb Hybrids - Shelby 5 5 20* 27 6
Lake Moyer/Dekalb Hybrids - Schneider 2 5 5 12 20
LaPorte Rocke/Agri-Mgmt Solutions     4 41 9
Madison Truster/Reynolds Farm Equipment   0      
Marshall Harrell/Harrell Ag Services   0      
Marshall Klotz/SR 10 & SR 331 0 0 0 8 9
Marshall Miller/North Central Coop 0 0 0 2 1
Miami Early/Pioneer Hybrids 0 0 0 3 2
Newton Moyer/Dekalb Hybrids - Lake Village 2 6 2 8 8
Porter Leuck/PPAC 5 3 18 25 8
Pulaski Capouch/M&R Ag Services 0 0 1 10 10
Pulaski Leman/North Central Coop   0 10 21 30*
Putnam Nicholson/Nicholson Consulting   2 6 2 8
Randolph Boyer/DPAC   1 0 1 2
Rush Schelle/Falmouth Farm Supply Inc.   6 10 1 3
Shelby Fisher/Shelby County Co-op 2 3 5 5 0
Shelby Simpson/Simpson Farms 7 49* 41* 67* 37
Starke Capouch/M&R Ag Services 0 0 6 28 21*
Starke Wickert/Wickert Consulting - California Twnshp 1 1 3 4 11
Starke Wickert/Wickert Consulting - Railroad Twnshp 0 0 0 0 9
St. Joseph Barry/Helena     1 3 15*
Sullivan Bower/Ceres Solutions - Farmersburg 0 1 2 14 18*
Sullivan Bower/Ceres Solutions - Sullivan 6 21* 14* 16* 6
Tippecanoe Bower/Ceres Solutions 0 0 0 7 3
Tippecanoe Westerfield/Monsanto Research Farm 0 0 13 11 16
Tippecanoe Nagel/Ceres Solutions 30 47* 44* 89 14
Tippecanoe Obermeyer/Purdue Entomology 2 5 11 5 20*
Tipton Campbell/Beck's Hybrids 10 17 11 73* 33*
Vermillion Bower/Ceres Solutions   0 0   0
Wabash Enyeart/North Central Coop       0  
Whitley Walker, Richards/NEPAC1 - Main 10 28* 37* 81* 87*
Whitley Walker, Richards/NEPAC2 - Kyler 3 8 17* 36* 33*

* = Intensive Capture...this occurs when 9 or more moths are caught over a 2-night period


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PLANT DISEASES




Managing Fusarium Head Blight (Scab) in Wheat(Kiersten Wise) -



Wheat growth stages vary greatly across the state, but as wheat is flowering in southern Indiana, or approaching flowering, it is important to consider the risk for Fusarium head blight (FHB), or scab, development.

The fungus that causes FHB, Fusarium graminearium, infects wheat during flowering, beginning at FGS 10.5.1. Symptoms appear later in the season and include bleached spikelets on the head (Figure 1), and small or shriveled grain kernels, commonly called “tombstones”. The fungus also produces mycotoxins, such as deoxynivalenol, or DON, which can accumulate in the infected grain.



Fusarium head blight.

Fusarium head blight.


Rainy, warm, and humid weather conditions favor disease development. It will be critical to watch the FHB risk assessment tool to assess the risk of Fusarium head blight in Indiana as wheat enters flowering over the next few weeks across the state. This model can be accessed through the following link: http://www.wheatscab.psu.edu/. This model uses weather information including temperature, rainfall, and relative humidity to calculate risk levels for FHB. The model has been updated in recent years, and now also includes an option to predict risk based on variety susceptibility to FHB. Keep in mind that the model does not provide a guaranteed prediction for whether or not FHB will occur in individual fields, and additional factors such as the local weather forecast, crop conditions, and Extension commentary should be considered when assessing the level of risk. Farmers and crop advisors can sign up for alerts courtesy of the U.S. Wheat and Barley Scab Initiative. Alerts can be sent to a cell phone or email, and will be sent out as the risk map updates risk of scab in Indiana. To sign up for alerts, visit: http://scabusa.org/fhb_alert.php.

If varieties susceptible to FHB have been planted, or farmers are worried about the risk of FHB development, they may want to consider a fungicide application at early flowering for suppression of FHB. Indiana research indicates that applications of the fungicides Prosaro and Caramba are most effective at managing FHB if they are applied at early flowering. Other products are available, but may not be as effective. Fungicides in the quinone-outside inhibitin (QoI) class (commonly called strobilurins) are not labeled for Fusarium head blight suppression. To accurately growth stage wheat and determine when wheat is beginning to flower, please see Purdue Extension publication ID-422 “Managing Wheat by Growth Stage”.

The foliar disease stripe rust (Figure 2) has been observed in fields in southern IN, but is still at relatively low levels. Purdue Extension Bulletin BP-79-W, “Identifying Rust Diseases of Wheat and Barley” is available to aid in diagnosis of stripe rust. It is important to consider variety susceptibility to stripe rust, growth stage, and disease spread before applying a fungicide for stripe rust management. Fungicides applied at flowering for FHB suppression will also provide some level of protection from foliar disease on the flag leaf. If farmers are considering a foliar fungicide application for stripe rust through boot stage, they should keep in mind that applications made prior to flowering will NOT suppress FHB or the associated mycotoxin deoxynivalenol, or DON. If the risk for FHB increases after foliar fungicide applications occur, it may be necessary to make another application at flowering for FHB suppression.



Stripe rust on wheat. (Picture courtesy Greg Shaner)

Stripe rust on wheat. (Picture courtesy Greg Shaner)


 

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WEATHER UPDATE




Precipitation



total precipitation


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Temperature



average temperature

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THANKS FOR READING




Contact Information

Purdue Extension Entomology
901 W. State Street
West Lafayette, IN, 47907
(765) 494-8761
luck@purdue.edu
@PurdueExtEnt
PurdueEntomology

1-888-EXT-INFO

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