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
Biocontrols 2015 Conference
CitrusGrowers Go In-Depth At Biocontrols 2015 Conference & Tradeshow
March 9, 2015
The first-of-its-kind event brought growers, researchers, regulators, and suppliers together for a two-day discussion on the latest biocontrols tools and technologies. Read More
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
CitrusMore California Citrus Placed Under Psyllid Quarantine
March 27, 2015
Asian citrus psyllid is found in Madera County – the heart of the San Joaquin Valley. Read More
FruitsAhead Of The Curve, Part 2
March 27, 2015
Get educated with great resources in the tree fruit industry available at your fingertips. Read More
Apples & PearsMeet USApple’s Class of 2015 Young Apple Leaders
March 27, 2015
Young decision-makers see trip as an opportunity make sure the voice of the apple industry is heard by representatives. Read More
GrapesGlassy-Winged Sharpshooter Found In Marin County
March 26, 2015
This pest, known to spread Pierce’s Disease, could devastate California winegrapes. Read More
GrapesFirst Raisin Grape That Dries Naturally On Vine Developed
March 26, 2015
The new Sunpreme variety eliminates the need for growers to cut into woody canes before harvest. Read More
Fresh From Florida Strawberry Parfait recipe
BerriesNew Partnership Sends Florida Strawberries To Puerto Rico
March 26, 2015
Latest addition extends Sunshine State’s agricultural export reach in the Caribbean. Read More
drought management; irrigation; water management
FruitsHow To Become A Soil Sleuth
March 26, 2015
To correctly apply the proper nutrients at the right rates, you need to know where your fields are deficient and how to correctly diagnose a disorder. Read More
NutsWhy You Should Use Low-Rate Applications Of Potassium
March 26, 2015
These rates provide growers a low-cost method comparable to conventional applications. Read More
Cold ProtectionWind Machine, Electric Pruners Donated To MSU Research Center
March 25, 2015
New equipment to help protect research blocks from frost damage and provide center with latest technology. Read More
CitrusProposed Farm Bill Provision To Limit Payments To Non-Farmers
March 25, 2015
USDA has proposed a new rule which would limit payment to those who are only actively engaged in farming. Read More
The Latest
CitrusMore California Citrus Placed Under Psyllid Quarantine
March 27, 2015
Asian citrus psyllid is found in Madera County – the heart of the San Joaquin Valley. Read More
FruitsAhead Of The Curve, Part 2
March 27, 2015
Get educated with great resources in the tree fruit industry available at your fingertips. Read More
Apples & PearsMeet USApple’s Class of 2015 Young Apple Leaders
March 27, 2015
Young decision-makers see trip as an opportunity make sure the voice of the apple industry is heard by representatives. Read More
GrapesGlassy-Winged Sharpshooter Found In Marin County
March 26, 2015
This pest, known to spread Pierce’s Disease, could devastate California winegrapes. Read More
GrapesFirst Raisin Grape That Dries Naturally On Vine Develop…
March 26, 2015
The new Sunpreme variety eliminates the need for growers to cut into woody canes before harvest. Read More
Fresh From Florida Strawberry Parfait recipe
BerriesNew Partnership Sends Florida Strawberries To Puerto Ri…
March 26, 2015
Latest addition extends Sunshine State’s agricultural export reach in the Caribbean. Read More
drought management; irrigation; water management
FruitsHow To Become A Soil Sleuth
March 26, 2015
To correctly apply the proper nutrients at the right rates, you need to know where your fields are deficient and how to correctly diagnose a disorder. Read More
NutsWhy You Should Use Low-Rate Applications Of Potassium
March 26, 2015
These rates provide growers a low-cost method comparable to conventional applications. Read More
Cold ProtectionWind Machine, Electric Pruners Donated To MSU Research …
March 25, 2015
New equipment to help protect research blocks from frost damage and provide center with latest technology. Read More
CitrusProposed Farm Bill Provision To Limit Payments To Non-F…
March 25, 2015
USDA has proposed a new rule which would limit payment to those who are only actively engaged in farming. Read More
Pennsylvania hard cider guild logo
Apples & PearsPennsylvania Hard Cider Producers Founded Independent T…
March 25, 2015
The Pennsylvania Cider Guild is designed to help promote and educate members and consumers. Read More
FruitsHow To Get Started With Partnerships And Sponsorships
March 25, 2015
Mark Saunders of Saunders Farm says your business is never too small or too big to get more value for what you do on your farm. Read More
FruitsValue Through Partnerships And Sponsorships [Opinion]
March 25, 2015
Mark Saunders of Saunders Farms says admission is one way to get value for what you do, but sponsorships and partnerships are the next level. Read More
chateau hough urban vineyard Cleveland Ohio
GrapesFrom Riots To Vineyard — A Story of Urban Revival
March 25, 2015
Ex-convict’s inner-city vineyard in the Hough neighborhood in Cleveland an opportunity for those leaving incarceration for a bright future in viticulture. Read More
FruitsWorld Ag Expo 2015: New Tools For Fruit Growers
March 24, 2015
From wind machines to solar-powered pumps, here is some of the new equipment on display this year's edition of the nation's largest farm show. Read More
Apples & PearsNeedles Found In Honeycrisp Sold At Grocery Store
March 24, 2015
Apples were believed to be tampered with; initial surveillance footage was inconclusive. Read More
Summer Foley gets crowned Miss Florida Citrus 2015 by 2004 winner Nikki Upthegrove Matthews and reigning Miss Florida Vicotria Cowen
CitrusMeet The New Miss Florida Citrus
March 24, 2015
Pageant marks comeback of longstanding industry tradition. Read More
Disease ControlBacterial Spot Can Make Almonds Unmarketable
March 24, 2015
Management strategies can help you mitigate losses from this nasty almond disease. Read More