New Info On Nematodes In Blueberries

Editor’s Note: This is the third article in a three-part series covering blueberry-related educational sessions from the Southeast Regional Fruit and Vegetable Convention in Savannah, GA, in January. Thanks to SBI Industries, manufacturer of TotalGro water soluble fertilizer, for sponsoring this month’s report.

Rabbiteye cultivars continue to dominate commercial blueberry production in Georgia, although more and more acreage has been devoted to southern highbush varieties. Recently, new rabbiteye and southern highbush varieties have been introduced, and due to superior characteristics, producers are replanting established blueberry sites.

With this replanting has come new discussions concerning fumigation. Fumigation, though practiced with many fruit commodities such as strawberries and peaches, had not been a recommended practice for new establishment of blueberries. However, it is not known whether fumigation would be of benefit in blueberry replant sites. Information has been sketchy and anecdotal at best.

An initial trial was conducted by University of Georgia (UGA) researchers in 2007 in Alapaha, GA, to review replant disorder in blueberries. At that point, replant disorder, if it existed, was assumed to be related to fungal organisms, especially Phytophthora and Pythium species. However, the results in this trial indicated that only the fumigants impacted the plant health of replanted blueberries. The fungicide Prophyt (phosphonate, Helena Chemical) did not impact the replants in any way, so oomycetes were not of major significance in this trial site.

Nematode Presence
The chart below indicates survey results of plant-parasitic nematodes in commercial blueberry plantings in Georgia in June 2010.
Nematode Species Percent Frequency* Mean Density/100 cm3 soil**
Ring (Mesocriconema ssp.) 48 290
Stunt (Tylenchorhynchus ssp.) 8 18
Stubby Root (Paratrichodorus ssp.) 8 13
Lance (Hoplolaimus ssp.) 7 130
Sheath (Hemicycliophora ssp.) 6 46
Awl (Dolichodorus ssp.) 2 19
Dagger (Xiphenema ssp.) 2 16

* = Percent of total samples with species present, N=289 samples from Appling, Atkinson, Bacon, Berrien, Brantley, Clinch, Cofee, Jeff Davis, Lanier, Pierce, Ware, and Wayne Counties

** = Mean population density for samples with nematode species present

 

In light of this data, UGA nematologist Jim Noe suggested checking for nematodes, and the results were interesting. Nematodes were previously not thought to be an issue on blueberries, and in fact, most sources of information indicated no or limited nematode activity in blueberries.

A closer look at ring nematodes indicated that perhaps more research was necessary. Ring nematodes obtain their name from the deeply striated cuticle. Various ring nematodes (Mesocriconema species) are known to cause damage on other fruit commodities, but the association with blueberries has never been established. However, large numbers of these root feeders could possibly be of importance, the researchers noted, due to direct activity and causing damage and stress for other pathogens.

Creating A Link

With this in mind, UGA researchers set out to confirm the importance of replant disorder in blueberries, and address nematodes as associated with replant disorder. Field fumigation trials were established at two sites (Alma and Homerville, GA) with five different treatments. Data was collected related to plant vigor and survival. Nematode data was also collected from each site, and ring nematodes were consistently associated with these sites.

Initial results indicated substantive benefits in vigor and plant health of plants following fumigation, especially as related to decreased ring nematode populations. The nematode counts at Alma were much less than those found in the Homerville site, and the degree of the fumigant effect was also greater at the Homerville site. At both locations, PicChlor 60 (60% chloropicrin, 40% Telone) provided good management of nematodes. A lower rate of Telone II was not sufficient for strong control of ring nematodes in these trials, though this rate will often control nematodes. At both sites, the untreated plastic only control did provide a vigor increase. It is presumed that there is some solarization effect involved in this, but this is not fully understood.

A subsequent survey of nematodes in blueberries in July 2010 indicated that ring nematodes are prevalent in replant sites. Ring is consistently a very high count nematode species, but others, such as lance, are also high count where they occur. However, ring was found in half of the blueberry sites in south Georgia.

In addition to noting the link between ring nematodes and stunting with replant disorder, the researchers also evaluated reproduction rates of ring nematodes under greenhouse and field conditions. It is important to note that these were short-term studies, and high populations of nematodes actually crash, whereas low populations build up. The bottom line, however, is that the ring nematode can survive and multiply on blueberries.

Down The Road

New information developed in the last two years indicates that stubby root appears to be a potential nematode issue in the Pacific Northwest, and there are distinct differences in cultivars as to their susceptibility. This indicates that breeding for nematode resistance may be critical to the long-term health of blueberry plantings.

The research into blueberry replant issues will not stop here. Future studies will look at:
• Additional research to further confirm the nematode connection to replant disorder
• Post-plant nematicides
• Solarization studies with plastic
• New pre-plant nematicides
• Rotation crops.

Leave a Reply

Featured Stories
Crop ProtectionAt Paramount Farming, Mating Disruption Pays Off
February 10, 2015
To say Brad Higbee is an expert in mating disruption, the use of pheromones to confuse target pests and reduce Read More
Crop ProtectionGrower Experienced In Biocontrols Says: Be Patient
February 4, 2015
The use of biocontrols in all aspects of agriculture is becoming more widespread. But incorporating biocontrols in a vegetable farming Read More
PotatoesAn Education On Potatoes [Opinion]
March 5, 2015
What is often a no-brainer for someone entrenched in the business of agriculture has to be explained — in detail — to some industry outsiders. Case in point: look at the rollercoaster ride potatoes have been on for several years. Read More
Insect & Disease Update#CitrusMatters Campaign Aims To Raise Awareness Of HLB In California
March 5, 2015
Bayer CropScience pledges up to $25,000 in support of continued research on a cure for citrus greening. Read More
CitrusNew Marvel Comic Book Reveals Origin Of Captain Citrus
March 5, 2015
Second installment of the Avengers Assemble series sets the stage for a new hero to save an orange grove under attack. Read More
FertilizerValent BioSciences Acquires Mycorrhizal Applications Inc.
March 4, 2015
Transaction fueled by technology platform that promises to bolster biorational business. Read More
EquipmentVegetable Growers Highlight Success With Precision Ag Technology
March 4, 2015
From prescriptive applications of water and fertilizers to seeders, precision technology has a place in any size operation. Read More
FruitsWeed Identification Guide Now Available For Growers
March 4, 2015
New free guide from Ohio State University offers high-definition pictures to help growers identify weeds. Read More
Crop ProtectionSurvey Shows Growers Seek New Strategies To Control Thrips And Other Major Pests
March 4, 2015
Growers surveyed at the 2015 Southeast Regional Fruit And Vegetable Conference list thrips as major pest concern, and are looking for new technologies to combat pests. Read More
Sweet CornAbbott & Cobb Sweet On New Sweet Corn Technology
March 3, 2015
SuperSeedWare gene type to aid varieties through marker-assisted selection. Read More
FruitsWest Coast Ports To Open With New Contract
March 3, 2015
Western fruit, vegetable industries lost millions when unable to export produce at ports. Read More
FruitsWorkshop Set In Florida To Help Grow Local Food Movement
March 2, 2015
Meeting part of nationwide effort to train people how to attain grants for USDA’s Farmers Market and Local Food Promotion programs. Read More
The Latest
PotatoesAn Education On Potatoes [Opinion]
March 5, 2015
What is often a no-brainer for someone entrenched in the business of agriculture has to be explained — in detail — to some industry outsiders. Case in point: look at the rollercoaster ride potatoes have been on for several years. Read More
Insect & Disease Update#CitrusMatters Campaign Aims To Raise Awareness Of HLB …
March 5, 2015
Bayer CropScience pledges up to $25,000 in support of continued research on a cure for citrus greening. Read More
CitrusNew Marvel Comic Book Reveals Origin Of Captain Citrus
March 5, 2015
Second installment of the Avengers Assemble series sets the stage for a new hero to save an orange grove under attack. Read More
FertilizerValent BioSciences Acquires Mycorrhizal Applications In…
March 4, 2015
Transaction fueled by technology platform that promises to bolster biorational business. Read More
EquipmentVegetable Growers Highlight Success With Precision Ag T…
March 4, 2015
From prescriptive applications of water and fertilizers to seeders, precision technology has a place in any size operation. Read More
FruitsWeed Identification Guide Now Available For Growers
March 4, 2015
New free guide from Ohio State University offers high-definition pictures to help growers identify weeds. Read More
Crop ProtectionSurvey Shows Growers Seek New Strategies To Control Thr…
March 4, 2015
Growers surveyed at the 2015 Southeast Regional Fruit And Vegetable Conference list thrips as major pest concern, and are looking for new technologies to combat pests. Read More
Sweet CornAbbott & Cobb Sweet On New Sweet Corn Technology
March 3, 2015
SuperSeedWare gene type to aid varieties through marker-assisted selection. Read More
FruitsWest Coast Ports To Open With New Contract
March 3, 2015
Western fruit, vegetable industries lost millions when unable to export produce at ports. Read More
FruitsWorkshop Set In Florida To Help Grow Local Food Movemen…
March 2, 2015
Meeting part of nationwide effort to train people how to attain grants for USDA’s Farmers Market and Local Food Promotion programs. Read More
Citrus18 Must-Have Apps For GenNext Growers
March 1, 2015
We asked about your favorite mobile applications, and here's what you had to say. Read More
Florida Ag ExpoGrowers Get The Lowdown On Cooling Crops
March 1, 2015
Demonstration shows how hydrocooling can help get the most out of fruits and vegetables once harvested. Read More
FruitsDon’t Be Afraid To Charge More For Value Of Agrit…
February 28, 2015
A higher admission price helps to sets a level of expectation and helps offset the costs of running a successful farm marketing operation. Read More
Apples & PearsCompany Responsible For First GMO Apples Is Sold
February 27, 2015
Okanagan Specialty Fruits, the company behind the world's first non-browning apples, fetches $41 million. Read More
Stone FruitPeach Training Systems Aren’t One-Size-Fits-All
February 27, 2015
Although pedestrian, ladderless orchards are increasing in California, growers in Pennsylvania are opting for tall V-training systems. Read More
FruitsNo Federal Water For California’s Central Valley Grower…
February 27, 2015
Skimpy snowpack leads Bureau of Reclamation to make unprecedented announcement that there will be a zero initial allocation for the second year in a row. Read More
Apples & PearsThe Recession That Keeps On Taking
February 27, 2015
We’re still seeing the aftermath of the Great Recession on consumers’ purchasing habits seven years later. Read More
Grower Achievement AwardSubmit Your Nomination For The 2015 Grower Achievement …
February 27, 2015
American Vegetable Grower magazine's annual award is designed to recognize an innovative operation that represents the spirit of excellence. Read More