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Friday, November 22, 2019

New Aphid to watch out for if you grow strawberries or blackberries

A heads up for any of you growing strawberries or blackberries out there… This new aphid might be something to watch for in early spring.”


Blayne Reed
EA-IPM Hale & Swisher
225 Broadway, Suite 6
Plainview, TX 79072
Office - 806-291-5267

Subject: Adventive Aphid and Natural Enemy Found in Mississippi

ARS News Service

ARS News Service

Aphis ruborum adult.
Aphis ruborum adult.

Adventive Aphid and Natural Enemy Found in Mississippi

By Sandra Avant
November 20, 2019
Agricultural Research Service (ARS) scientists and their colleagues have discovered, for the first time, an adventive—meaning it just arrived in a new locality—aphid species as well as an associated parasitoid wasp on strawberry plants in Stoneville, Mississippi.
While sampling for plant pests and natural enemies, Eric W. Riddick, a research entomologist with the ARS Biological Control of Pests Research Unit, found the aphid, Aphis ruborum,on cultivated strawberries in his research high tunnels—unheated greenhouses.  It's not supposed to be here, he said. The species has spread in Europe, north Africa, India, Pakistan, Chile, Argentina, western United States (Washington state) and Canada.
The aphid was found predominately on newly emerged, not fully developed leaflets of daughter strawberry plants in 2016, Riddick said. By 2017, aphids were observed on fully developed leaflets on mother plants. The occurrence of A. ruborum in Mississippi represents a new state record and the eastern-most established record in the United States, he added.
The study, recently published in the Journal of Insect Science, cites another discovery. In 2017, Riddick found mummified aphids, which signaled that a parasitoid wasp, Aphelinus varipes, had attackedthe aphid. The tiny wasp, which is a beneficial insect, is not known to attack this species of aphid.
This is first time an attack by the A. varipes waspon the A. ruborum aphidhas been documented anywhere in the world, Riddick said. The wasp layseggs that develop inside the aphid, killing it. ARS scientists in Beltsville, Maryland, identified the aphid, and non-ARS colleagues at the University of Georgia and Agriculture and Agri-Food Canada identified the parasitoid wasp, using molecular techniques.
The aphid seldom uses cultivated strawberry as a host plant, Riddick said. However, it frequently attacks blackberries, damaging foliage. As it feeds, the aphid also injects a virus, which can cause plants to wilt and die.
The next step is to figure out where the aphid came from. It is possible that previously undetected populations of the aphid have survived on uncultivated plants (such as wild strawberry, dewberry or blackberry) in the landscape surrounding Stoneville. Riddick plans to conduct a small-scale sampling for the aphid on wild plants in areas around Stoneville and study the rate at which the aphid is being attacked by the parasitoid.
The Agricultural Research Service is the U.S. Department of Agriculture's chief scientific in-house research agency. Daily, ARS focuses on solutions to agricultural problems affecting America. Each dollar invested in agricultural research results in $20 of economic impact.

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Wednesday, November 20, 2019

Cotton Irrigation Timing Study released

A Texas A&M AgriLife Research study looked at irrigation timing to maximize water-use efficiency and yields. (Texas A&M AgriLife photo by Kay Ledbetter)

Cotton is sensitive to water stress at different growth stages, needing water at specific times to produce a high-yielding crop. A Texas A&M AgriLife Research study investigated the best strategies to improve irrigation water-use efficiency while maintaining high yields.
Evaluation of crop-growth-stage-based deficit irrigation strategies for cotton production in the Southern High Plains,” was authored by AgriLife Research scientists Srinivasulu Ale, Ph.D., geospatial hydrologist, and Sushil Himanshu, Ph.D., postdoctoral research associate, both in Vernon, and James Bordovsky, senior agricultural engineer, Halfway, along with and Murali Darapuneni, New Mexico State University.  The study was published in Agricultural Water Management Journal’s special issue on Managing the Ogallala.

Himanshu said the study should help farmers make better decisions that can result in higher seed cotton yields using the most efficient irrigation strategies. At the same time, these strategies will conserve the Ogallala Aquifer as a water resource for generations to come.

Researchers focused on irrigation strategies based on cotton’s five growth stages, with certain stages irrigated more and others less. The CROPGRO-Cotton module available in the Decision Support System for Agrotechnology Transfer Cropping System Model was used. This crop growth-simulation model allows testing and analysis of different irrigation scenarios.

The Southern High Plains are hot, dry and often windy with water shortages due to the region’s low rainfall and reliance on underground water. Cotton-boll size and count are greatly affected by the amount and timing of irrigation as well as rainfall and air temperature.

Additionally, water districts in the area have imposed restrictions on groundwater pumping to help conserve the Ogallala Aquifer. Depletion of the aquifer has been occurring at an alarming rate since the 1950s when farmers began large-scale water pumping for crop irrigation.

“Following the suggested strategies, farmers can have better control over crop growth and yield and enhance irrigation water-use efficiency,” Ale said. “The peak bloom growth stage was found to be the most sensitive stage to water stress and imposing water deficit during this stage resulted in the lowest seed cotton yield.”

Conversely, elimination of irrigation during the early and late-season growth stages had little effect on seed cotton yield and irrigation water-use efficiency.

“We also determined that reducing early season irrigation potentially increased cotton root growth,” Bordovsky said. “This helps plants have a stronger resilience to water shortages in later growth stages and increased seed cotton yield.”

Cotton Incorporated and the Ogallala Aquifer Program funded this study.

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