Category: Crops

Guess the Pest! Week #18 Answer: Western Bean Cutworm

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Bill Cissel, Extension Agent – Integrated Pest Management, University of Delaware; bcissel@udel.edu

Congratulations Bob Leiby for correctly identifying the moth as a western bean cutworm and for being selected to be entered into the end of season raffle for $100 not once but five times. Everyone else who guessed correctly will also have their name entered into the raffle. Click on the Guess the Pest logo to participate in this week’s Guess the Pest challenge!

Guess the Pest Week #18 Answer: Western Bean Cutworm
by Bill Cissel, Extension Agent, Integrated Pest Management and David Owens, Extension Entomologist

The western bean cutworm (WBC) is native to the western United States where it is considered a pest of corn and dry beans. Despite the name, they actually do not “cut” plants. Western bean cutworm are univoltine, meaning they have a single generation per year and overwinter as pre-pupa. In the spring, they pupate and adult moths emerge in early June. Female moths will lay eggs throughout July and August on both wild and cultivated plants. Field corn in the whorl stage prior to pollination is a preferred oviposition site. Eggs are typically laid on the upper leaf surface near the whorl in masses of 20-200 eggs which take approximatley 7 days to hatch. Larvae undergoe six instars before burrowing into the soil to pupate. Since the early 2000s, WBC has spread, causing economic damage as far east as NY, MI, OH, WI, and Ontario. Studies conducted in Nebraska and Iowa suggest an infestation averaging one larva per ear can cause yield losses reaching as high as 4 bu/A. Larvae bore through the side of the ear and open the ear up to mycotoxin-causing fungal colonization. Most Bt traits do not adequatley control this pest.

We first detected WBC in Delware in 2011 after capturing a few moths in a pheromone trap in New Castle Coutny. We captured 14 moths in 2012 and have not trapped for this pest since 2012 until 2018. This year, we have been monitoring 10 pheromone traps located throughout the state and have captured four moths to date. We will continue to monitor for this pest throughout the growing season but at this point, it appears that WBC populations remain low for us in Delaware. By comparison, states where western bean cutworm causes signficant injury to corn catch dozens of moths per week in a single trap.

2012 Western Bean Cutworm Trap Summary: http://s3.amazonaws.com/udextension/ag/files/2012/06/2011WesternBeanCutwormTrapSummary.pdf

2013 Western Bean Cutworm Trap Summary: http://s3.amazonaws.com/udextension/ag/files/2012/06/2012-Western-Bean-Cutworm-Trap-Summary2.pdf

Here is a link to a Fact Sheet from Purdue University with more detailed information on the identification, biology, and damage of the Western Bean Cutworm: https://extension.entm.purdue.edu/fieldcropsipm/insects/western-bean-cutworm.php

Fun Entomology Fact: It is not unusual to find an ear infested with multiple western bean cutworm larvae because they are not canabalistic like corn earworms.

Guess the Pest! Week #17 Answer: Soybean Leafminer

 

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Bill Cissel, Extension Agent – Integrated Pest Management, University of Delaware; bcissel@udel.edu

Congratulations Julie Knudson for correctly identifying the damage in the photo as soybean leafminer damage and for being selected to be entered into the end of season raffle for $100 not once but five times. Everyone else who guessed correctly will also have their name entered into the raffle. Click on the Guess the Pest logo to participate in this week’s Guess the Pest challenge!

Guess the Pest Week #17 Answer: Soybean Leafminer
By David Owens, Extension Entomologist, owensd@udel.edu

This week’s Guess the Pest is an interesting but rather unimportant member of the defoliating insect complex. The soybean leafminer (Odontota horni) adult is a beautiful red, flattened, rectangular beetle with red wings and prothorax and black head, antennae, legs, and a black stripe down the middle of the back. The black stripe doesn’t reach all the way to the end of the wings. Adults are active beginning around early to mid-June. They lay eggs on the underside of leaves, and the larvae immediately mine into the leaf. Larvae spend their entire lives between the upper and lower leaf surface, leaving a quarter sized brown blotch. When larvae complete development, they pupate in the mine. Immatures require 30 – 40 days to fully develop into adults. There is only one generation per year. Beetles will continue to lightly skeletonize leaves and over the course of their adult life might feed on the equivalent of one leaflet until they migrate out of fields to find overwintering shelter in late summer. Beetles and larvae are never present in any significant populations.

There are a couple of other beetle leafminers that you may see this summer. The most obvious and abundant is the locust leafminer, Odontota dorsalis. It pretty much stays confined to locust and can cause a large amount of locust defoliation by August. So, as you drive along the highway and notice trees with a brown cast to them, you may be seeing locust leafminer. Locust trees can handle the defoliation and leaf back out.

Guess the Pest! Week #16 Answer: Spider Mite

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Bill Cissel, Extension Agent – Integrated Pest Management, University of Delaware; bcissel@udel.edu

Congratulations Jeffrey O’Hara for correctly identifying the damage in the photo as spider mite damage and for being selected to be entered into the end of season raffle for $100 not once but five times. Everyone else who guessed correctly will also have their name entered into the raffle. Click on the Guess the Pest logo to participate in this week’s Guess the Pest challenge!

Guess the Pest Week #16 Answer: Spider Mite

The damage in the photo is from two-spotted spider mite (TSM) feeding on soybean. Hot, dry weather favors TSM and drought can trigger outbreaks. TSM populations are held in balance by natural enemies and the weather. Under high temperatures, the amount of time required for TSM to complete its lifecycle is shortened, allowing more generations to be completed in a shorter period of time. A female TSM can produce 300 offspring in her lifetime (~30 days) and most of the individuals in the population are female. Dry conditions also diminish the activity of fungal diseases that often play a key role in keeping outbreaks from occurring.

So, if it rains, does it mean we don’t need to worry about TSM? Precipitation not only favors spore formation and mite infection but also reduces plant stress. This however isn’t always a silver bullet and TSM populations can continue to increase even after rain events, especially if the weather returns to being hot and dry. Cool nights and humid conditions promote the fungal disease that infects TSM.

Below is a graph showing rain events and observed TSM populations in the untreated check from a TSM field trial conducted in Georgetown, DE in 2017:

Observed Influence of Precipitation on Two-Spotted Spider Mite Populations, 2017

Weather data obtained from the Delaware Environmental Observing System (DEOS): http://www.deos.udel.edu/data/agirrigation_retrieval.php

As you can see in the graph, TSM populations continued to increase and remained high despite rain events occurring on 7/22, 7/23, 7/25, and 7/28.

To scout for TSM, examine the underside of 5 leaflets in 10 locations for mites, noting the presence of mite eggs and the amount of leaf damage. The threshold for TSM during bloom to podfill is 20-30 mites per leaflet and 10% of plants with 1/3 or more leaf area damaged.

Concentrate scouting efforts on field edges for initial detection, especially edges bordered by grass and road ditches (it’s not unusual to also find hot spots in the interior portions of the field). TSM typically develop on grasses and other plants on field borders before ballooning into fields. Once TSM are detected, scout the interior portions of the field to determine if they have spread throughout the entire field. If only concentrated on field edges, spot treating may be an option. If spot treating on field edges, extend the treated area about 100 feet further into the field from the damaged area.

Here is a link to our Soybean Insecticide Recommendations for chemical control options if your field is at threshold for TSM: https://cdn.extension.udel.edu/wp-content/uploads/2018/05/02102500/Insect-Control-in-Soybeans-2018.pdf

Can Timing and Method of Barley Cover Crop Termination Impact Pests and Beneficials within a Subsequent Soybean Planting?

Alan W. Leslie, Armando Rosario-Lebron, Guihua Chen and Cerruti R. R. Hooks
Department of Entomology, College of Computer, Mathematical, and Natural Sciences

Summary

This extension article is meant to serve as a condensed write-up of a completed field study. Full-text of the published work can be viewed via open access at http://www.mdpi.com/2073-4395/8/6/87. Cover cropping has long been used as a method of reducing soil erosion, increasing soil quality, and suppressing weeds. However, impacts of cover crops in cropping systems differ and can be affected by timing and method of their termination. Field trials were conducted over two field seasons and at two sites in Maryland to examine how varying the date and method of terminating a barley (Hordeum vulgare) winter cover crop affects arthropods (insects and spiders) in succeeding no-till soybean (Glycine max) plantings. Experimental treatments included early-kill with pre- and post-emergent herbicides (EK), late-kill with pre- and post-emergent herbicides (LK), late-kill with a flail mower and pre-emergent herbicide (FM), and a fallow/bare-ground check with pre- and post-emergent herbicides (BG). Terminating barley late (i.e., just prior to soybean planting) resulted in significantly greater biomass accumulation in LK and FM than EK. However, method and timing of termination had no effect on communities of pest and beneficial arthropods in the soybean canopy. Results from this experiment suggest that terminating the cover crop early or late or using a mower or burn-down herbicide to kill the cover crop will result in similar species and number of arthropods within the soybean canopy.

Introduction

Cover cropping can be a viable weed management tool in conservation agriculture systems. When cover crops are terminated in reduced- and no-till cropping systems, resulting residues that remain on the soil surface can help prevent weed establishment. Thus, it is well known that cover crop residue impacts weed populations. More specifically, some of these studies were designed to examine how method and timing of cover crop termination practices impact weed populations in grain crops. However, impacts of these practices on arthropod populations are rarely considered. Despite this, studies have shown that cover crops can impact arthropod numbers in succeeding agronomic crops. Some insect pests shown to be impacted by cover crop residue include the potato leafhopper (Empoasca fabae), bean leaf beetle (Cerotoma trifurcata), and Japanese beetle (Popillia japonica) in soybean as well as thrips in cotton (Gossypium hirsutum). In addition to insect pests, their natural enemies may be influenced by cover crop residue.

The overall goal of this study was to investigate how different cover crop termination practices impact populations of insect pests and their natural enemies within no-till soybean plantings. Specific objectives were to compare the influence of termination method (chemical versus mechanical) and timing (early versus late) on arthropod populations. Barley was chosen as the test cover crop partially because of its accessibility and popularity among producers.

Materials and Methods

Field experiments were conducted at the University of Maryland’s Central Maryland Research and Education Center at the Upper Marlboro and Beltsville farm sites in 2013 and 2014. Each field experiment consisted of four treatments, including three cover crop termination methods and a fallow/bare-ground control. The three cover crop treatments included: (1) early-kill (EK), in which the cover crop was sprayed with post- and pre-emergent herbicides in mid-April; (2) late-kill (LK), in which the cover crop was sprayed with post- and pre-emergent herbicides in late May; and (3) flail-mowed (FM), in which the cover crop was sprayed with a pre-emergent herbicide and mowed in late May. An early-kill, flail-mowed treatment was not included in the experiment because mowing typically does not kill cover crops at early stages of development and farmers do not use this method. The bare-ground treatment (BG) remained fallow after the previous crop was harvested and received the same post- and pre-emergent herbicide applications as LK.

The EK treatment was sprayed with a post- and pre-emergent herbicide mixture on 15 April at Beltsville and 16 April at Upper Marlboro in 2013 and on 18 April at both sites in 2014. The LK treatment was sprayed with a post- and pre-emergent herbicide mixture on the day soybeans were planted. The BG treatment received the same spray protocol as LK. On the day soybeans were planted, the FM treatment was sprayed with a pre-emergent herbicide and the cover crop was mowed. The soybean was planted on 21 May at Beltsville and 20 May at Upper Marlboro in 2013 and 27 May 2014 at both sites. Soybeans were planted in wide rows [76 cm (30 inch) inter-row spacing] at Beltsville and narrow rows [18 cm (7 inch) inter-row spacing] at Upper Marlboro. A late-season herbicide application was applied to all plots at the Beltsville location as a “rescue” herbicide treatment primarily for large crabgrass (Digitaria sanguinalis).

Data collection. Data on vegetative (cover crop and weed) biomass, abundance of weeds and arthropods, soil moisture as well as yield were collected during this investigation. Data on weed population, soil moisture and yield will be presented in a future edition of Agronomy News. To quantify cumulative barley and weed biomass production, cover crop and weed biomass were measured in each plot just prior to their termination. Arthropod abundances were monitored with the use of a sweep net from the R1 through R5 soybean growth stages. Arthropods collected were divided into i) natural enemies (predators – arthropods that prey on herbivores & parasitoids – insects, especially wasps, that complete their development within the body of another insect eventually killing it) and ii) herbivores (insects that feed on plants). Arthropods were separated further according to seven feeding habits (guilds). The seven feeding habits that we used included 1) chewing predators, 2) sucking predators, 3) parasitoids, 4) plant-sucking herbivores, 5) pod feeders, 6) foliage feeders and 7) spiders. Though they are predators, spiders were placed into a separate predatory feeding guild.

Results

Vegetative biomass. At each farm site, flail-mowed (FM) and late-killed (LK) treatments had higher plant biomass than early-killed (EK) or bare-ground (BG) treatments (Table 1). Total barley biomass in LK and FM treatments were more than two times greater at Beltsville than Upper Marlboro. No differences were detected in plant biomass between BG and EK treatments within each site, but there was greater weed biomass in the BG treatment at Beltsville than Upper Marlboro (Table 1).

Table 1. Cover crop and weed dry biomass just prior to their termination.

Site Treatment Mass ± SEM (kg ha−1)
Beltsville Early Kill 160.1 ± 60.5 cd1
Late Kill 2211.9 ± 83.2 a
Flail Mow 2123.4 ± 112.9 a
Bare Ground 896.0 ± 254.3 bc
Upper Marlboro Early Kill 85.8 ± 21.2 d
Late Kill 753.4 ± 100.9 b
Flail Mow 851.8 ± 62.7 b
Bare Ground 120.4 ± 27.2 d

1Different letters indicate that means are significantly different.

Arthropod Counts. In total, 54 families of arthropods were collected from sweep samples which included a total of 11,344 specimens (Table 2). Approximately 98% of arthropods collected could be assigned to one of the seven feeding guilds used. Three feeding guilds, which included plant-sucking herbivores (25%), foliage-feeding herbivores (24%), and sucking predators (21%), accounted for 70% of the entire arthropod community sampled.

The abundance of arthropods from each feeding guild was similar among treatments. However, there was a significant effect of soybean development stage on all feeding guilds. In general, parasitoid, chewing predator, and sucking predator guilds reached greatest abundance later in the season (R4 or R5 stage). In contrast, numbers of foliage feeding and plant sucking herbivores peaked earlier in the growing season at the R2 or R3 stage (Table 3). Sucking predators and spiders were found in greater numbers in Beltsville than Upper Marlboro across all soybean growth stages.

Table 2. Arthropod feeding guilds, families and their abundances. Numbers represent total abundance across all sample dates.

Beltsville Upper Marlboro
Feeding Guild Family 2013 2014 2013 2014
Spider Salticidae 25 47 24 48
Araneidae 5 69 0 37
Oxyopidae 149 101 42 94
Thomisidae 18 16 35 11
Lycosidae 0 12 0 26
Clubionidae 0 3 0 0
Ctenidae 0 1 0 0
Tetragnathidae 0 8 0 9
Linyphiidae 0 4 0 2
Pholcidae 0 1 0 0
Parasitoid Platygastridae 159 11 57 0
unspecified1 0 407 0 104
Sceleonidae 10 23 1 15
Chalcididae 0 2 0 3
Proctotrupidae 0 1 0 2
Braconidae 0 76 0 29
Eulophidae 0 18 0 5
Ichneumonidae 0 8 0 3
Tiphiidae 0 178 0 25
Aphelinidae 0 1 0 1
Encyrtidae 0 1 0 0
Mymaridae 0 0 0 1
Eurytomidae 0 0 0 1
Trichogrammatidae 0 0 0 2
Chewing predator Asilidae 5 6 0 0
Mantidae 1 1 1 0
Coccinellidae 21 262 36 193
Carabidae 0 5 0 3
Syrphidae 0 101 0 4
Cantharidae 0 0 0 1
Sucking predator Geocoridae 543 346 223 326
Pentatomidae 3 8 1 1
Chrysopidae 5 1 3 13
Anthocoridae 48 166 225 161
Nabidae 100 340 37 93
Hemerobiidae 0 10 0 3
Reduviidae 0 0 0 4
Foliage feeder Coccinellidae 287 92 43 1
Erebidae 346 756 274 455
Meloidae 0 1 0 0
Scarabaeidae 428 284 90 96
Chrysomelidae 2 345 0 254
Noctuidae 0 1 0 0
Hesperiidae 0 3 0 0
Plant sucking Cicadellidae 32 732 109 689
Membracidae 22 0 40 18
unspecified 404 0 896 0
Aphididae 0 0 0 60
Pod feeder Pentatomidae 33 164 69 115
Miridae 112 102 108 229
Unassigned unspecified 0 2 67 30
Chrysomelidae 0 0 0 2
Curculionidae 2 5 0 30
Lampyridae 4 21 17 5
Lygaeidae 0 0 0 0
Elateridae 18 5 0 12
Noctuidae 0 0 0 1
Apidae 0 0 1 0
Cynipidae 0 0 18 3
Vespidae 0 0 5 8
Chrysididae 0 0 3 3
Pompilidae 0 0 1 0
Scoliidae 0 0 1 0
Thyreocoridae 0 0 0 14
Berytidae 0 0 0 41
Alydidae 0 0 0 2

 1Unspecified taxa were not identified to the family level.

 


Table 3. Means (± standard errors) of feeding guilds within farm site and soybean development stage.

Abundance per 10 Sweeps
Feeding Guild Site1 R1 R2 R3 R4 R5
Spider BV 1.22 ± 0.26 a2 0.91 ± 0.20 a 1.27 ± 0.13 a 2.02 ± 0.25 a 1.28 ± 0.22 a
UM 1.19 ± 0.33 a 0.58 ± 0.11 a 0.96 ± 0.10 a 1.19 ± 0.18 a 1.25 ± 0.19 a
Parasitoid BV 0.97 ± 0.20 b 1.28 ± 0.28 ab 1.23 ± 0.15 ab 3.33 ± 0.52 a 4.81 ± 0.92 a
UM 0.22 ± 0.11 b 0.56 ± 0.12 ab 0.72 ± 0.14 ab 0.97 ± 0.16 ab 1.28 ± 0.38 a
Chewing predator BV 0.63 ± 0.33 b 0.13 ± 0.05 ab 0.82 ± 0.15 ab 1.25 ± 0.24 ab 1.56 ± 0.30 a
UM 0.28 ± 0.10 b 0.02 ± 0.02 ab 0.48 ± 0.10 ab 1.59 ± 0.31 ab 1.50 ± 0.31 a
Sucking predator BV 3.75 ± 0.69 b 3.41 ± 0.51 b 4.03 ± 0.37 ab 8.27 ± 0.65 a 6.41 ± 0.73 ab
UM 2.13 ± 0.34 b 2.59 ± 0.35 b 2.03 ± 0.18 ab 7.84 ± 1.05 a 5.91 ± 0.64 ab
Foliage feeder BV 8.78 ± 0.92 b 7.50 ± 0.86 ab 9.62 ± 0.70 a 6.25 ± 0.85 b 4.06 ± 0.86 b
UM 2.81 ± 0.95 b 1.84 ± 0.26 b 5.17 ± 0.41 a 2.89 ± 0.36 ab 2.41 ± 0.52 b
Plant sucking BV 6.81 ± 1.16 ab 5.66 ± 0.61 a 2.73 ± 0.21 ab 3.20 ± 0.43 b 2.22 ± 0.32 b
UM 3.81 ± 0.72 a 8.61 ± 1.01 a 2.97 ± 0.19 a 15.0 ± 3.66 a 8.38 ± 1.77 a
Pod feeder BV 0.81 ± 0.24 a 0.64 ± 0.15 a 1.23 ± 0.16 a 0.50 ± 0.14 a 1.34 ± 0.36 a
UM 1.00 ± 0.21 a 1.73 ± 0.28 a 1.09 ± 0.15 a 1.69 ± 0.29 a 3.50 ± 0.66 a

1BV = Beltsville, UM = Upper Marlboro

2Different letters within individual rows represent significant differences between growth stages.

 


Discussion

The objective of this study was to quantify the impact of cover crop termination method and timing on arthropods within soybean foliage. Cover crop termination practices are known to impact arthropods via resulting residues that remain on the soil surface. Thus, it was believed that different cover crop termination methods examined during this study would influence arthropod abundances differently. As expected, delaying the cover crop termination date resulted in significantly greater biomass of residue in late-kill (LK) and flail-mowed (FM) than in early-kill (EK) treatments. Averaged across years, delaying cover crop termination in FM and LK increased barley biomass relative to EK by 2007.5 kg ha−1 (1791 lbs/acre) at Beltsville and 716.8 kg ha−1 (639.5 lbs/acre) at Upper Marlboro. However, arthropod populations within the soybean foliage responded similarly to treatments regardless of plant biomass differences. Instead, arthropod abundances changed according to soybean growth stage. Chemical (LK) and mechanical (FM) termination tactics also had similar effects on arthropod abundances. This suggests that whether cover crops are killed early or late, or chemically or mechanically by mowing, the resulting arthropod community will be similarly impacted. The EK “early” (early April) and LK “late” (at soybean planting from mid to late May) treatments represent some of the most widely used practices for cover crop termination by Mid-Atlantic soybean producers. The results of our study suggest that these two practices are likely to result in similar species and number of foliar arthropods throughout the different soybean growth stages.

Conclusions

Overall, our results indicate that cover crop termination methods that result in greater cover crop biomass will have no effect on insects and spiders within the soybean foliage. However, if delaying cover crop termination results in greater weed suppression without impacting soybean productivity, this practice should nevertheless make soybean systems more resilient to pest pressure and acceptable by soybean producers.

Acknowledgments

We thank crews at the Upper Marlboro and Beltsville Research and Education Centers for logistics in establishing and completing field trials. This work or publication was supported by Hatch Project No. MD-ENTO-9107/project accession no. 227029 and the Crop Protection and Pest Management (CPPM), Extension Implementation Program (EIP) award number 2017-70006-27171 from the USDA National Institute of Food and Agriculture, and funding from the Maryland Soybean Board.

Guess the Pest! Week #15 Answer: Stink Bug

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Bill Cissel, Extension Agent – Integrated Pest Management, University of Delaware; bcissel@udel.edu

Congratulations Chris Leon for correctly identifying the damage in the photo as stink bug damage and for being selected to be entered into the end of season raffle for $100 not once but five times. Everyone else who guessed correctly will also have their name entered into the raffle. Click on the Guess the Pest logo to participate in this week’s Guess the Pest challenge!

Guess the Pest Week #15 Answer: Stink Bug

The damage on the corn stalk is stink bug feeding injury. Stink bugs will use their piercing-sucking mouthparts to probe into the stalk of the plant, removing plant fluids. If the stink bug hits the ear at this stage, the ear will often fail to develop kernels at the feeding site. This causes the ear to develop into the classic “C”-shaped or boomerang-shaped ear. This is why the greatest damage and yield loss potential due to stink bug feeding is prior to pollination. This is also why waiting until after tasseling (pollination), to control a stink bug infestation in field corn is too late. Here is a link to last week’s article discussing stink bug management in field corn: http://extension.udel.edu/weeklycropupdate/?p=12194

Guess the Pest! Week #14 Answer: Corn Rootworm

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Bill Cissel, Extension Agent – Integrated Pest Management, University of Delaware; bcissel@udel.edu

Congratulations to Kathleen Heldreth for correctly identifying the damage in the photo as corn rootworm damage and for being selected to be entered into the end of season raffle for $100 not once but five times. Everyone else who guessed correctly will also have their name entered into the raffle. Click on the Guess the Pest logo to participate in this week’s Guess the Pest challenge!

Guess the Pest Week #14 Answer: Corn Rootworms

The corn plants in the photo are damaged by corn rootworm larvae. As you can see, the larvae feed on the roots and root tissue of the plants causing the plant roots to be “pruned”. Older larvae will tunnel into the roots leaving visible entrance holes and blackened root tips. Plants with excessive root pruning will usually lodge and in reaching for the sun, become “goosenecked”. Corn rootworm infestations are unusual for Delaware and not something we typically have to manage for. Crop rotation is the preferred method of control in regions with sporadic populations. Corn rootworm females prefer to lay eggs in corn fields in August and September. The eggs do not hatch until the following spring. If the field is rotated out of corn, the larvae will starve to death in the absence of a suitable host plant.

Controlling Perennial Weeds in No-Till Fields

Kelly Nichols, Agriculture Agent Associate
University of Maryland Extension, Frederick County
kellyn@umd.edu

Perennial weeds like pokeweed, hemp dogbane, and horsenettle can flourish in no-till corn and soybean fields. Without tillage to break up the roots, perennial weeds can continue to regrow every year. Here are a few tips on how to control perennial weeds in your fields.

pokeweed in corn field
Figure 1. Pokeweed in a no-till corn field. Image: Kelly Nichols, University of Maryland.

Use a residual herbicide to prevent seedlings from germinating later in the summer. Those later-emerging seedlings may still have time to become established enough to survive the winter and re-grow the following spring.

Apply post-emergent herbicides at the proper time. About the time that the perennial weeds are producing flower buds and blooms (approximately mid-summer), they begin to send food reserves down to the roots. Since things are moving in a downwards direction in the plant, the herbicide is more easily taken down to the roots, which will provide better control. A late post-emergent application is more possible in soybeans, which are a shorter-statured plant. One benefit from the wet spring and late-planted fields is that the corn is shorter than normal at this time of year, making a late post-emergent herbicide application possible in corn as well.

Rotate the field into other crops. In an alfalfa field, perennial weeds will not be able to withstand the frequent mowing. It depletes the food reserves in the root, weakens the plant, and reduces the chance for winter survival. Small grains that are harvested for grain will compete with the perennial weeds trying to grow in the spring and summer. An herbicide application could follow the harvest to control any late-summer weed emergence.

The Mid-Atlantic Field Crop Weed Management Guide provides herbicide recommendations and information for agronomic crops. To purchase a pdf or hard copy, visit the Penn State Extension website. To view a low-resolution pdf for free, visit the University of Delaware Extension website

4R Technology Field Day

4R Field day

The Delaware-Maryland 4R Alliance and University of Maryland Extension invite growers and agribusiness professionals to join them for their 4R Technology Field Day on August 15, 2018 at the Wye Research and Education Center in Queenstown, Maryland. The event will be showcasing application of the 4Rs (right source, right rate, right time, and right place) on the Delmarva. Demonstrations will include phosphorus placements, drones and mapping, options for nitrogen management and conservation practices and water quality monitoring. There will also be a panel of local farmers discussing how they have been successful in implementing 4R nutrient management practices in their operations.

Registration will begin at 8:30 am and the program will be from 9:30 – 2:30. Lunch will be provided as well as Nutrient Management and Certified Crop Advisor credits. We ask that you register so we can get an accurate count. To register please visit: technology-field-day-tickets.eventbrite.com

The Delaware-Maryland 4R Alliance is a partnership between agribusinesses, farmers, researchers, conservation organizations, and local, state, and federal agencies that encourages the application of the right fertilizers at the right time, the right rate, and in the right place. This framework of nutrient management was first established by The Fertilizer Institute. The Chesapeake Bay Program has recognized this type of nutrient management as a critical foundation to successfully reducing nitrogen and phosphorus loss on farms.

For more information, contact Danielle Bauer, (443) 262-8491, Danielle.mdag@gmail.com.

 

Know Your Insect Pests: Soybean Thrips

Emily Zobel, Agriculture Agent Associate
University of Maryland Extension, Dorchester County
ezobel@umd.edu

Soybean thrips on soybean leaf
Adult soybean thrips. Image: J. Obermeyer, Purdue Extension.

Soybean thrips are a common insect pest species found in soybean across the United States. However, thrips feeding injury rarely causes economic damage since plants easy outgrow it under favorable environmental conditions.

Thrips are small (0.8- 5 mm) slender insects. The larvae are yellow in coloration, and the adults have bands of brown and white across their body, with fringed wings. Adults and larva feed by scraping the cell walls on the underside of leaves until they rupture. The insect then feeds on the exuding sap. Leaves with heavy feeding damage often have a silver or gold dotted look.

Insecticidal treatment is not ordinarily justified unless populations are unusually high and plants are environmentally stressed, due to hot, dry conditions. Fields should be scouted for thrips by checking the middle trifoliolates of 100 random plants. If over 75% of the sampled trifoliolates are damaged, and there is an average of 8 thrips per leaf, treatment may be advisable. If natural enemies are presents or favorable weather is predicted, then treatment is not needed.

 

LEAD Maryland Accepting Applications

LEAD MD logoThe LEAD Maryland Foundation is seeking applications for the next class of LEAD Fellows. The LEAD Fellowship Program works to increase the numbers and capacities of leaders serving agriculture, natural resources, and rural communities. Program participants will complete a series of multi-day seminars held throughout Maryland and Washington, D.C., along with a travel study and class project in 2019 and 2020 .

Program information, calendar, and link to the on-line application are available at: extension.umd.edu/lead-maryland.

All interested applicants are encouraged, before submitting an application, to coordinate and communicate with co-workers, supervisors, family members, or any others who may need to support the applicant. Fellows will need time away from other responsibilities to fully complete the fellowship, and need to pay a participation fee (tuition).

Completed applications and references are due October 1, 2018.

The LEAD Maryland Fellowship Program is a University of Maryland Extension program serving the entire state. The LEAD Maryland Foundation funds a large share of the program and governs many aspects of the fellowship management. Contact Susan Harrison at (410) 827-8056 or leadmd@umd.edu for more information.