Last year we reported on waterhemp in Montgomery and Macon counties that was resistant to dicamba. We came to this conclusion from both research we conducted in the fields and the confirmation of those results by greenhouse research. The greenhouse research was conducted at Purdue University by my colleague Dr. Bill Johnson and his graduate student Claudia Bland. Continue reading
As most Tennessee soybeans are entering their mid-late reproduction growth stages, some symptoms of diseases caused by soil-borne pathogens may be beginning to show up in our fields, particularly sudden death syndrome this year. The issue with diagnosing diseases caused by soil-borne pathogens is that they often exhibit very similar symptomology to each other. However, there are certain indicators that can help you differentiate between these diseases and help you make the best management decisions moving forward. Continue reading
Driving across West Tennessee last week it is very apparent we have taken a step backward on Palmer amaranth control. Many fields that looked clean from the road in late July are now showing large Palmer amaranth escapes. Upon closer inspection the pigweed escapes are at least partially affected by the dicamba applications which resulted in them staying hidden from the road until the last couple of weeks. Continue reading
Wondering what’s been making your soybeans sickly? Come to The University of Tennessee Soybean Disease Field Day, held Tuesday, Sept. 12th, at the Milan Research and Education Center. Registration will be from 8:30-9:00 AM with the tour beginning at 9 AM and concluding with a box lunch. Preregistration is not required. Pesticide re-certification and CCA points will be available. Continue reading
| Location | CEW | TBW |
| Hardeman (Bolivar) | 2 | 0 |
| Fayette (Whiteville) | 3 | 0 |
| Fayette (Somerville) | 12 | 0 |
| Shelby (Millington) | 4 | 0 |
| Tipton (Covington) | 3 | 0 |
| Tipton (North) | 3 | 0 |
| Lauderdale (Golddust) | 8 | 0 |
| Haywood(West) | 9 | 0 |
| Haywood (Brownsville) | 15 | 1 |
| Madison (WTREC) | 9 | 0 |
| Madison (North) | 0 | 0 |
| Crockett (Alamo) | 0 | 0 |
| Crockett (Friendship) | 2 | 0 |
| Dyer (King Rd) | 12 | 0 |
| Dyer (Dyersburg) | 1 | 0 |
| Lake (Ridgely) | 12 | 0 |
| Gibson (Trenton) | 30 | 0 |
| Gibson (Milan Rec) | 0 | 0 |
| Carroll (Coleman Farm) | 8 | 0 |
Numbers are consistently going down across West TN and this is the last week for trap catches.
I’ve received a few calls this week on corn earworms (bollworm/podworm) showing up in fields across Tennessee. UT’s threshold for earworms, in beans, is based on sweep net sampling, crop value and control costs. The table below outlines the threshold based on the above factors.
Crop value is on the left-hand side, control costs are the 3rd row from the top and numbers beneath control costs are earworm numbers per 25 sweeps. The spot price of beans for (8/31) is $13.75 and control costs can vary from $10 to $16, depending on product choice, so the threshold in 25 sweeps would be 5 to 6 earworms per 25 sweeps. As crop price and control cost changes so does the number of earworms in our threshold.
Moths are typically attracted to later planted, more open canopy fields. However, earworms can be found in any stage beans. Insecticide choice depends on a few factors. If earworms are at or near threshold, acephate (0.75 lb/a) plus a pyrethroid is a cheaper option that provides acceptable control. This option runs the risk of flaring other pests (loopers, mites) and fields need to be rechecked 4-5 days after application to makes sure adequate control was achieved. If worms are above threshold safer choices would be Vantacor (1.2 fl oz), Elevest (5.0 fl oz), Besiege (7.0 fl oz), Intrepid Edge (4.0 fl oz) or Blackhawk (2.0 oz). The diamides (Vantacor, Besiege, Elevest) will have the longest residual control but many earworm issues in TN beans are solved after one application.
Another, more nonconvention option is Heligen (1.0 – 1.5 fl oz). Heligen is earworm specific and doesn’t have a fit on every acre. Applications should be initiated on small larvae at half a threshold (typically 2 – 4 larvae in 25 sweeps). Heligen is a virus that spreads throughout the field via infected larvae and requires some patience and knowledge of infection symptomology.
One final note, this product should almost be looked at as a preventative not a curative product. However, worms have to be in the field for the virus to infect the target and replicate causing an epizootic. Large populations of earworms, at or above threshold, need a conventional insecticide.
| Location | CEW | TBW |
| Hardeman (Bolivar) | 6 | 0 |
| Fayette (Whiteville) | 29 | 0 |
| Fayette (Somerville) | 26 | 0 |
| Shelby (Millington) | 42 | 0 |
| Tipton (Covington) | 2 | 0 |
| Tipton (North) | 20 | 0 |
| Lauderdale (Golddust) | 35 | 0 |
| Haywood(West) | 8 | 1 |
| Haywood (Brownsville) | 67 | 0 |
| Madison (WTREC) | 41 | 1 |
| Madison (North) | 35 | 0 |
| Crockett (Alamo) | 1 | 1 |
| Crockett (Friendship) | 51 | 0 |
| Dyer (King Rd) | 48 | 1 |
| Dyer (Dyersburg) | 61 | 0 |
| Lake (Ridgely) | 35 | 2 |
| Gibson (Trenton) | 98 | 0 |
| Gibson (Milan Rec) | 4 | 0 |
| Carroll (Coleman Farm) | 15 | 2 |
| Location | CEW | TBW |
| Hardeman (Bolivar) | 3 | 0 |
| Fayette (Whiteville) | 31 | 1 |
| Fayette (Somerville) | 12 | 0 |
| Shelby (Millington) | 36 | 0 |
| Tipton (Covington) | 4 | 0 |
| Tipton (North) | 15 | 0 |
| Lauderdale (Golddust) | 17 | 0 |
| Haywood(West) | 21 | 1 |
| Haywood (Brownsville) | 26 | 0 |
| Madison (WTREC) | 48 | 3 |
| Madison (North) | 18 | 0 |
| Crockett (Alamo) | 1 | 2 |
| Crockett (Friendship) | 27 | 0 |
| Dyer (King Rd) | 44 | 1 |
| Dyer (Dyersburg) | 45 | 1 |
| Lake (Ridgely) | 20 | 2 |
| Gibson (Trenton) | – | – |
| Gibson (Milan Rec) | 2 | 5 |
| Carroll (Coleman Farm) | 20 | 0 |
Due to the excess rainfall we experienced over the past week, we weren’t able to reach our Trenton location. If moth numbers are exceedingly high, I’ll update the post and send out those numbers tomorrow.