Aug 13, 2021
Solving the parasitic nematode problem: a preventative approach

{Sponsored} When growers redevelop an orchard, it’s imperative that certain steps are taken to ensure fast growth and plant health. Ultimately, it’s difficult to control what happens in an open orchard setting, but by properly preparing the soil, growers can expect that many potential problems will be mitigated, resulting in better long-term results. 

The Problem 

Since nematodes and other potentially pathogenic organisms can be found not just in the top layer of soil, but also within several feet of depth, it’s difficult to adequately treat the soil using conventional methods; this often results in often patchy protection. Nematode hot zones may be visible in existing orchards and are indicated by uneven growth, in absence of other causes. Preventing these hot zones can help ensure that fertilizer and water are not wasted due to underuse. 

With the added variable of how long roots can survive and provide shelter and food for those organisms, and with estimates up to several years, it takes the right soil treatment, in addition to the correct preparation, to net the results growers need from their young orchards. 

Recommended IPM Strategy for young orchards 

Uniformity throughout an orchard helps improve efficiency of growth, fertilizer and water use, and a consistent harvest. Using an integrated pest management strategy can alleviate the problems associated with a lack of uniformity in the orchards. These steps will set up an orchard for better success — with faster growth. 

  1. Test the soil. Take samples, especially in areas where there were patchy spots, and send them to the local university or nematology lab for testing; this will provide a window into the nematode pressure in the orchard. 
  2. Deep Rip. After removing retired trees from the orchard, using a backhoe to fracture the soil up to six feet deep and to the sides helps to generate a growth response in new trees, according to a Merced County university study. 
  3. Remove old roots. Take the time to remove old roots as soon as possible. The pest populations will start to dissipate as soon as infected roots are removed. Allow as much time as possible between root removal and fumigation. 
  4. Thoroughly till soil. Break up the clumps and clods, preparing the soil not only for young roots but also to allow fumigant to fully permeate the full volume of soil that will be treated. This will also assist the soil as it seals at the surface. 
  5. Fumigate. Use a pre-plant fumigant such as Telone® II in a broadcast application, which can help prevent future hotspots. Another option, in orchards where there is a known fungal or bacterial problem, is to use a Telone/Chloropicrin blend at this step. “Growers have to make critical decisions whether to do strip vs. broadcast. However, when there is nematode pressure within a field, the pressure can be found between the tree rows, and over time the pressure can move. Once rootstock is planted, plant parasitic nematodes can sense root exudates and move towards the root system to feed, causing infection. If a grower cannot do broadcast, it is best to follow up with post treatment contact nematicides through the seasons to help reduce nematode infection,” said Kristi Sanchez, Ph.D, Nematologist for TriCal and TriCal Diagnostics. For best results, fumigation should be done in the fall. 
  6. Plant cover crops. Choose a crop that is not susceptible to nematodes but which also has a long root. A crop such as safflower will help to dry out the soil, desiccating any surviving nematodes in preparation for planting trees. 
  7. Choose the right root stock. Consider resistant or tolerant roots that will not be as susceptible to nematodes; this is especially important in areas where nematode pressure was high, based on the soil testing performed at the start of the process. 
  8. Ongoing IPM strategy. Fumigation isn’t possible after planting, but it will give your orchard a fighting chance. Continuing to manage nematodes is important to keeping that advantage the orchard will get from the careful preparation and fumigation.

    Orchard growth, untreated control vs Telone II with Chloropicrin
    Orchard growth, untreated control vs Telone II with Chloropicrin

Trial results with Telone fumigation 

“Telone is a key step in a multistep IMP strategy to give growers the best shot at suppressing nematodes and maintaining healthy orchards,” Sanchez said. 

In trials, Telone fumigation prior to planting has resulted in significant increases in trunk diameter, tree height and overall canopy size compared to untreated trees. The field trials being conducted by the University of California have initially shown a cumulative yield increase of 80% over trees not treated with Telone, measured from 2013 through 2018. In the trial, planting was done in 2011 in treated sandy soil that previously had heavy nematode pressure, including ring, lesion and root knot nematodes. 

About Telone II 

Telone II soil fumigant is a preplant soil fumigant for control of all major species of nematodes, including root-knot, lesion, stubby-root, dagger, ring and cyst. Telone II is injected into the soil as a liquid and immediately converts to a gas, creating a zone of protection around developing roots. As a fumigant, Telone moves throughout the soil profile without requiring water or incorporation for movement. Learn more about Telone at 

 ®™Telone is a trademark of The Dow Chemical Company. Telone is a Federally Restricted Use Pesticide. Always read and follow label directions. 

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