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Publication #SS-AGR-55

Precision Agriculture and Planting the Same Row Patterns Influence on Cotton and Impact on Reniform Nematodes1

D. L. Wright, S. George, and J. R. Rich2

Reniform (Rotylenchulus reniformis) and root knot (Meloidogyne incognita) nematodes have become an increasingly important problem in cotton production in the United States and Florida. Management of nematodes is accomplished by crop rotation, nematicides, or a combination of these practices since complete resistance of cotton cultivars is not available. However, there are some varieties on the market that have some level of resistance to root know nematode. For many growers, rotation is not seen as an option because of low alternative commodity prices, and the most effective nematicides are very costly or have been taken off the market. Thus, practices need to be developed to provide more flexibility to manage nematodes. Our research using strip-till planting has centered on cultural practices that could potentially reduce cotton losses from nematodes at little cost to growers. These have included planting cotton between previous crop rows, increasing cotton plant populations, and destroying cotton roots soon after harvest. In a preliminary trial, cotton planted strip-till between previous cotton rows showed positive results. Cotton lint yield was increased 29% by planting between previous rows as compared to planting into the old cotton row. Further tests, as described here, have confirmed the usefulness of planting between previous cotton rows to reduce losses from reniform nematodes. Precision farming techniques allow farmers to plant back over the row from the previous year to take advantage of the subsoil slot or fertilizer that was applied in the row. However, this may result in a yield reduction. There is a consistent yield reduction for each year in coton without rotation. The perennial nature of cotton allows roots to continue growing late into the fall until a killing frost occurs.

Two field trials, one each year, were conducted at the North Florida Research and Education Center near Quincy, FL, on a loamy sand soil (80% sand, 8% silt, 12% clay) infested with reniform nematodes. Cotton was grown on this site the year before, and the mowed stubble was left undisturbed over the winter. Two cotton cultivars using Roundup and Bt technology were planted using strip tillage in late June of each year. Rows were 36 inches wide, and the two treatments consisted of planting cotton directly in-row over the old cotton stubble or planting between the previous cotton rows. The treatments were alternated and replicated six times. Cotton was maintained using standard cultural practices for Florida. Soil samples for nematode analysis and plant yield were collected from two rows per plot. When soil samples were taken concurrently in the cotton row and between rows, individual cores were taken across from each other to insure comparable sampling areas. Soil was collected for reniform nematode extraction and counted using standard techniques. Cotton was harvested with a spindle picker in early December in the two tests, and subsamples ginned for lint yield.

In Test 1, reniform nematode population densities 28 days after planting were lower in cotton planted between previous rows than where planted over the previous rows (Table 1). As the season progressed, reniform nematode population densities in-row in both treatments increased and were roughly equal 76 days after planting. Samples taken after 136 days were collected both in-row and between rows of the two treatments. Reniform nematode population densities were significantly higher in-row in both treatments (mean-1603/100 cm3 soil) compared to row middle populations (mean-544/100 cm3 soil). Cotton yield mirrored early season nematode population density. Yield was significantly higher in cotton planted between previous cotton rows compared to in-row planting.

In Year 2, initial reniform nematode population densities were lower between previous cotton rows than those taken in the old cotton row (Table 2). At both the 81 and 153 day sampling dates, reniform population densities did not differ between the two treatments (Table 3). Additionally, nematode population densities between row middles of both previous-year treatments did not differ from each other but were significantly lower than those found in the planted row of either treatment. Due to the initially lower populations of reniform nematodes in rows middles, however, cotton lint yield was significantly higher than in-row plantings (Table 2).

Present information supports the idea that planting cotton in previous row middles when strip-till planting will help avoid a portion of potential yield losses due to reniform or other nematodes. This is due to population densities of reniform nematodes that are less between rows as compared to in-row populations. However, plant growth, hence root spread, is probably an important factor in the success of this technique. Auto steer and other current technology make it easy for growers to plant between previous cotton rows or directly back over the old row. As nematode population is determined throughout the field by direct sampling or by electrical conductivity, variable rate nematicide application is feasible and is becoming more common place as knowledge about fields are obtained. However, we do know that row middle plantings could increase nematicide performance. Also, shifting to row middle plantings using strip-till technology does not involve additional grower expense so any yield improvement would be profitable for the cotton farmer.

Concern about compaction has often been the motivating factor in planting back over the old row instead of in previous row middles. This research indicates that where reniform nematodes (and probably rootknot nematodes) are a problem, it pays to strip till in row middles. Compaction in row middles should not be a problem, with the use of chisels or subsoilers, and yields are significantly higher than planting back over last year's row where higher nematode populations exist.


Table 1. 

Comparative reniform nematode population densities in cotton planted in the row or between rows of a previous cotton crop, Test 1.

Planting Method*

Days after planting






Nematodes/100 cm 3 soil






Row Middle





* In-row planting indicates that cotton was seeded over the row from the previous year; row middle cotton was planted between rows from the previous year.

** Column means followed by the same letter are not significantly different (P < 0.05).

Table 2. 

Initial populations of reniform nematodes and lint yield of cotton planted in-row and in row middles of a previous cotton crop, Test 2.

Planting method




100 cm3 soil*




Row middle



* Indicates initial nematode population densities; samples were collected eleven days prior to planting.

** In-row planting indicates cotton was seeded over the row from the previous year; row middle cotton was planted between rows from the previous year.

*** Column means followed by the same letter are not significantly different (P < 0.05).

Table 3. 

Comparative reniform nematode population densities in cotton planted in-row and in row middles of a previous cotton crop.

Sampling method

Days after planting



Nematodes/100 cm3 soil

In-row planting*

In-row samples



Row middle samples



Row middle planting

In-row samples



Row middle samples



* In-row planting indicates cotton was seeded over the row from the previous year; row middle cotton was planted between rows from the previous year.

** Column means followed by the same letter are not significantly different (P < 0.05).



This document is SS-AGR-55, one of a series of the Agronomy Department, UF/IFAS Extension. Original publication date July 2002. Revised July 2006, September 2012, and November 2015. Visit the EDIS website at


D. L. Wright, professor, Agronomy Department; S. George, biological scientist; and J. R. Rich, professor emeritus, Entomology and Nematology Department, North Florida Research and Education Center; UF/IFAS Extension, University of Florida, Gainesville, FL 32611.

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U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.