64 AMERICAN POTATO JOURNAL [Vol. 48

ROW FUMIGATION WITH VORLEX FOR CONTROL OF A MEADOW NEMATODE

(PRATLYLENCHUS PENETRANS) IN POTATOES

ARTHUR HAWKINS 1 AND P. M. MILLER 2

ABSTRACT

Row fumigation with Vorlex at 3 and 7 gallons per acre was applied for meadow nematode (Pratylenchus penetrans) control in potatoes. The material was applied 3 weeks before planting using one chisel per row at a depth of 8", and ridged.

The treatments resulted in a reduction in population of P. penetrans in the soil and in the potato roots. On a soil with a relatively high population of meadow nematodes, row application of Vorlex at 3 and 7 gal per acre resulted in a yield increase of 10 and 14% respectively, and a lower incidence of tubers with vascular discoloration. By early October as many nematodes were present in treated rows as in untreated rows. Row fumigation is of value for only one potato crop.

Nematode control for potatoes by soil fumigation (chisels 8" to 10" apart) has been found to result in marked improvement in vine growth and yield increases of 20 to 60%, especially in fields with high counts of meadow nematode (Pratylenchus penetrans) in Connecticut (2, 3, 4).

The objective of the experiments in 1968 reported here was to determine the effect of preplant row fumigation with Vorlex on control of nematodes and yield of potatoes.

MATERIALS AND METHODS

The tests were located in fields in the Connecticut River valley which had been in potatoes previously for several years. The field at farm D had a moderately high population of meadow nematode averaging about 100 or slightly more per 5 oz soil sample. The field at farm H had about 40 nema- todes per 5 oz sample.

The soil at both locations had been plowed and disked just prior to row fumigation in late April. Vorlex was applied with a rear mounted tool bar equipped with two injection chisels spaced 34" apart to correspond with row spacing on the two-row planter (Fig. 1). By means of disks attached to the applicator, soil was simultaneously ridged above to a peak height of 9" and a width of 16" at the base (Fig. 2). At farm D comparisons were made between four untreated rows and four treated rows, in rows which would not be damaged by sprayer wheels. At farm H comparisons were in adjoining two-row plots. Untreated rows were also chiseled and ridged. Soil temper- ature at time of application was 50-52 F at both locations.

After about 2 weeks, the ridges were partially flattened by a weeder at farm D and by a suspended disk harrow at farm H, to aerate the soil. Katah- din potatoes were planted with a two-row planter which split the ridges, 22

aAgronomist, Storrs Agricultural Experiment Station, The University of Connecticut, Storrs, Connecticut. Accepted for publication September 29, 1970

2Plant Pathologist, Department of Plant Pathology and Botany, The Connecticut Agricultural Experiment Station, New Haven, Connecticut.

1971] HAWKINS AND MILLER: CONTROL OF MEADOW NEMATODE 65

FIG. 1.--Row fumigation applied with rear-mounted tool bar equipped with two injection chisels spaced to correspond with row spacing of planter.

FIG. Z--Row application of fumigant using one injection chisel per row, and bedding discs.

66 AMERICAN POTATO JOURNAL [Vol. 48

days after row fumigation at location D, 5 days after ridges had been par- tially flattened by a weeder; at location H potatoes were planted 17 days after fumigation, 2 days after ridges were part ial ly levelled off.

Samples of soil for nematode counts were taken in the ridge 22 days after fumigation at location D; the middle of the potato row was sampled on 7/21 at location H for nematode counts in soil and potato roots. Soil samples were also obtained from the middle of the rows at both locations on 10/2.

At both locations foliage infesting insects were controlled by insecticides appl ied as needed. Di-Syston was also applied for insect control at location H, at 2.2 Ib per acre at planting; it was not applied at location D.

Irr igation was applied as necessary at location D and with good insect control the vines lived late into the season and produced good yields. At location H irrigation was not applied during the dry spell in late August and vines deteriorated by mid-September and were vinekilled. Yields were ob- tained at location D on four untreated rows and on four adjoining treated rows; the rows were 471 ft long. The potatoes were mechanical ly harvested and conveyed into bulk trucks and weighed. At location H, yields were based on samples 2 rows x 40 ft from the 2-row comparisons.

RESULTS AND DISCUSSION

The 7 gal per acre rate of Vorlex was much more effective than the 3 gal rate in kill of nematodes in the ridge, as shown by nematode counts in samples of soil taken in the row 3 weeks after fumigation, farm D (Table 1).

TABLE 1. The effect of row tumigation on meadow nematode (Pratylenchus penetrans) 3 weeks alter treatment I, Farm D, Connecticut 1968.

P. penetrans in 100 grams of soil sampled 3 weeks after treatment 2

Vorlex In clods on 5"-6" below ridge Gal/A top of ridge surface 3

0 106 167 3 18 53 7 0 3 7 6 (top 1/2") 4 0 120 75 7 16 13

1Treated 4/50/68, one chisel per row 8" depth; soil ridged to 9" height. 2Soil sampled 5/22. .~Soil ridge broken down 2" to 3" with weeder on 5/17.

On this soil with a relatively high populat ion of meadow nematodes, row applicat ion of Vorlex at 3 and 7 gal per acre resulted in yield increases of 10 and 14% respectively (Table 2). A lower incidence of vascular discolor- ation was found in the tubers from treated rows than in tubers from un- treated rows (Table 3). Black scurf was worse in Vorlex-treated plots as was found before (5).

Soil samples taken from the middle of the rows on October 2 showed that the nematode populat ion had increased on treated rows to the same

1971] I - I A ~ r K I N S A N ~ M I L L E R : C O N T R O L O F M E A D O W N E M A T O D E 67

TABLE 2. Effect o~ row ]umigation with Vorlex on yield o] Katahdin pota- toes, Farm D I, Connecticut 1968.

Vorlex Total yield 2 Yield increase Gal /A cwt /A cwt /A Percent

Premium size whole seed--good stand 0 321 5 353 32 10

Cut-seed from A size--fair stand 0 300 7 341 41 13.7

1Row fumigated 4/30/68; ridges disturbed 5/17; planted 5/22/68. zYield based on 4 rows x 471 ft for each comparison.

TABLE 3. Effect o] row fumigation with Vorlex on tuber disease, Farm D - - Conn. 1968.

Vorlex Scurf % tubers with Gal /A rating 1 vascular discoloration2

0 1.8 14 3 2.5 5 7 3.0 2

aScurf rating is based on percent of tubers with sclerotia (scurf) of Rhizoctonia solani. With a rating of 1 = 0-25% of tubers have scurf; 2 = 25-50% have scurf; 3 = 50-75% have scurf; 4 --= 75-100% have scurf.

2Tubers cut 1/2-3/4" from stem end. 150 tubers were examined from each plot.

TABLE 4. Population o] nematodes in middle o] potato row in Jail, after row ]umigation in spring, Farm D, Connecticut 1968.

Row Vorlex gal per Acre

Nematodes 1 per 100 grams of soil 10/2/682

Meadow nematode Tobacco stunt nematode (P. penetrans) (T. claytoni)

11-12 0 22 23 15-16 3 24 3 25 & 28 0 39 12 29 & 32 7 40 14

1Average of 4 samples. 2Soil sample from middle of potato rows, 3 to 6" below top of row.

number as on unt rea ted rows at fa rm D (Table 4) , but to a lesser extent at f a rm H (Table 5).

There was a marked ly lower number of nematodes in the soil in the ridge and in the pota to roots in samples obta ined 7 /21 f rom rows t reated wi th the h igher rates of Vor lex at locat ion H (Table 5).

68

TABLE 5.

AMERICAN POTATO JOURNAL [Vol. 48

Effect of row fumigation on meadow nematodes (P. penetrans) in soil and potato roots, Farm H, Connecticut 1968.

Vorlex 1 Number of nematodes in Number 3 of nematodes in fumigation gal/A 6 cm roots z 100 grams soil4

7/21 7/21 10/2

0 21 14 90 3 21 11 54 5 0 1 54 7 0 1 22

1Row fumigation 4/30; ridges were disked lightly 5/15; Katahdin potatoes planted 5/17.

z6 cm = 2.4 inch. ZAverage of 4 counts each. 4Soil samples from middle of potato rows, 3 to 6" below top of row.

At location H, with a lower nematode populat ion, the increase in total yield was 6% from row fumigation at 7 gal per acre. The systemic Di-Syston which had been applied at planting time for aphid control had some effect on nematode control (1). A higher populat ion of nematodes was found where neither Di-Syston nor row fumigation had been applied.

A disadvantage of the row fumigation method is that potato planting must be deferred for at least 2 to 3 weeks or more after row treatment in the spring. On the other hand, fumigation by the regular method can be applied in the fall when conditions are usually better for more effective fumigation.

ACKNOWLEDGMENT

The assistance of Edward Ahronian in applying the material , and NOR-AM Agricultural Products Inc. in supplying the equipment and material is gratefully acknowledged. The cooperation and assistance of ]ohn D. and Donald S. Dzen of Rockville, Connecticut and Edward ]. and Ralph ]. Has- tillo, Rockville, on whose farms these experiments were conducted is grate- fully appreciated.

LITERATURE CITED

1. Hawkins, Arthur and P. M. Miller. 1971. Row treatment with systemics for nematode control for potatoes. Amer. Potato J. 48: 21-25.

2. Miller, P. M. and Arthur Hawkins. 1969. Long term effects of soil fumigation of potato fields. Amer. Potato J. 46: 587-397.

3. Miller, P. M., L. V. Edgington and Arthur Hawkins. 1967. Effects of soil fumi- gation on Verticillium wilt, nematodes and other diseases of potato roots and tubers. Amer. Potato I. 44: 316-323.

4. Miller, P. M. and Arthur Hawkins. 1967, Effects of fall fumigation on nema- todes, early maturity disease, yields, and vascular discoloration of tubers of Kennebec and Katahdin potatoes. Amer. Potato J. 44: 339.

5. Miller, P. M. 1957. A method for the quick separation of nematodes from soil samples. Plant Dis. Reptr. 41: 194.