David Doll2 CommentsOctober 27, 2014Diseases

Fall Sampling for Nematodes: Now is a Good Time

Late fall is a good time to consider nematode sampling. Sampling may be important to perform if lack of vigor or poor growth is observed within an orchard. Samples should be taken once the soil begins to cool in October. For best results, multiple soil samples should be taken, with a minimum of one sample per soil type present in the orchard. If soils are  relatively uniform,  two to three samples should be made for fields smaller than 60 acres. Five or six samples are needed for  for larger uniform fields. A composite of 5-7 different spots within the soil type or field quadrant should be pooled (mixed and combined) as one “sample.” Soil samples should be taken at a depth of 15″-20″ within the rootzone of the tree. Once enough samples have been collected, they should be placed in a properly labeled bag, kept cool and out of the sun, and submitted to a lab to conduct the nematode analysis. 

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David Doll2 CommentsDecember 7, 2012Diseases

Lasting Effects of Soil Fumigation on Nematodes?

I am often asked about the duration of control that pre-plant soil fumigation has on parasitic nematodes. My typical response is “Probably about 3-4 years, or once the roots move outside of the treated area.” This generalization appears to be true in many orchards as symptoms of nematode parasitism, which include stunting, bacterial canker, and bud drop, often do not develop until the fourth or fifth year. This past fall, we performed our annual nematode sampling of all of our research plots. One of the plots was our almond replant plot located near Ballico. This orchard is located on a sandy soil with a history of almond trees and nematodes. In the fall of 2010, it was fumigated with four fumigant treatments, including methyl bromide row-strip, C35 row-strip, Telone II rowstrip, and Telone II broadcast, a control plot, and a spot steam treatment. In the spring of 2011, the trees were planted.

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David Doll2 CommentsOctober 19, 2009Diseases

Sampling for Plant Parasitic Nematodes

Many growers are facing the question of replanting orchard blocks. This aspect of orchard maintenance is critical and essential in maintaining an orchard business. Outside of the general tree removal, soil and ground preparation, there are 3 key biological replant problems that must be taken in consideration when replanting. These include plant parasitic nematodes, aggressive soil pathogens and pests, and replant disease of almond. This blog will focus on the first mentioned aspect of replant problems: nematode sampling and nematode control. In almond production, there are three main parasitic nematodes that are of concern – Ring, Rootknot, and Lesion. Depending upon your soil type, planted rootstock, and previous cropping history, the populations of these nematodes can vary within the soil. It is important to keep in mind that plant parasitic nematode populations are directly related to tree production – in other words, the higher the number present, the more tree damage to expect. A previous blog describes the affect of nematodes on tree growth. Orchard Sampling to Determine Nematode Populations. To determine nematode populations, soil samples collected from the root zone area of a tree should be sent off to a laboratory for processing. In collecting samples, the following procedure should be used: 1. By using a soil map, identify soil texture changes within the orchard block, 2. Time the sampling to occur after the year of cover cropping or fallow period – if one occurred, 3. Attempt to sample from different soil textures and areas of previous tree performance. A good sampling strategy for a 40 acre block can be seen in figure 1. Please note the sampling in different soil textures and random samples throughout the field, 4. Use a soil tube and sample the 4″-16″ depth of the profile – this is the area of most active

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