AGRICULTURAL RESEARCH CENTER f,
Hastings, Florida .. Of
Himeo Research Rebort PR-1975-5 November 1974
IMPROVING POTATO YIELDS, TUBER QUALITY AND CONTROLLING CORKY RINGSPOT
DISEASE WITH NEMATICIDES. -D. P. Weingartner, Asst. Plant Pathologist
J. R. Shumaker, Assoc. Horticulturist. G. C. Smart, Jr., Nematologist,
D. W. Dickson, Assoc. Nematologist
INTRODUCTION: Potato soils in the Hastings area are infected with several
different plant parasitic nematodAs-whibh'-afeotfbo6th .yifidg a A'qvuaiity
of potatoes. This Mimeo Report suimarizes experiments performed during
1971-74 in wh4t* nonfumigating nematicides were evaluated for nematode
control, and for their effects on the yields and quality of potato tubers.
METHODS: Granular or liquid formulations of nonfumigating nematicides
were generally applied at 3.0 Ib. active ingredient (ai) per acre in-
the-row (3.7 oz. ai per 1000 feet of row). Chemicals were applied in
12-14 inch bands to surfaces of flattened rows. Depending upon the ex-
periment, chemicals were incorporated into the soil with a stalk chopper
or by the disking and planting action of the potato planter. Potatoes
were generally planted in January-February and harvested during May. Tuber's
were rated for overall quality on a 1-10 scale (l1no surface defects and
* !_=surface of all tubers totally affected). Corky ringspot disease (CRS)
S'as rated separately (l=all tubers free of 8 and 10=all tubers severely
affected by CRS).
RESULTS: (i) yields All chemicals which wee tested increased yields
in one or more experiments when compared to nontreated controls (Table 1).
Tamik 10G, Mocap 10G, and Furadan 10G, each at 3.0 lb ai per acre in-the
row, have most consistently improved yields. Nemacur 15G looked promising
during 1973-1974. In those experiments comparing soil fumigants and non-
fumigating chemicals, yields from Temik, Mocap, and Furadan treated plots
were qqual to or exceeded those treated with D-D (10GPA) or Telone ($GPA).
(ii) Tuber quality defects-Defects which were observed in the various
tests included secondary growth, abnormal russetting, deep surface
fissures and growth cracks. Causes of such defects have not been
determined, however Rhizoctonia spp., tobacco rattle virus (causes CRS),
injury from nematodes feeding on developing tubers, or a combination of
these could be involved.
As shown in Table 2, both fumigants and nonfumigating nematicides improved
tuber quality when compared to nontreated controls. However when quality
defects were severe, nonfumigating chemicals were superior to soil fumigants.
In one experiment performed during 1973, for example, Telone (80PA) improved
tuber quality by 6.7% whereas Furadan 4F (3.0 Ib al) improved quality by 44.0%
(iii) Corky ringspot disease Data from two experiments performed during
1974 are summarized in Table 3. Non fumigating chemicals significantly
reduced CRS when compared to the nontreated control. The disease tended
to be more severe in plots treated with Telone.
SUMMARY: Yields from Temik, Mocap, ard Furadan treated plots have consistently
been greater than those from nontreated controls and have been equal to or
superior to yields from plots fumigated with D-D or Telone.
Nonfumigating nematicides, especially Temik and Furadan, have consistently
improved quality of potato tubers and have reduced both the incidence and
severity of CRS. Soil fumigants applied in-row have not effectively con-
Temik is registered nationally for use on potatoes and Mocap has been
granted a state use label. Although Dasanit is registered for use on
potatoes, as an insecticide, it has not provided effective nematode control
on potatoes in Florida at these rates, Furadan is not registered for use on
potatoes, and can not be used at this time.
Temik 10G and Mocap 10G, each applied at3.0 lb ai/acre in-the-row, are
recommended for use as .nematicides in Florida. Temik is suggested for
use in fields in which both nematodes and CRS are problems.
Table 1: Effects of nonfumigating nematicides and Telone on potato yields
in north Florida. Summary of nine experiments performed during 1970-1974.
No. of Mean Yields (cwt/acre)
Nematicide 1/ Experiments %
Conducted Treatments Controls increase in
Temik 10G 9 198 157 26.1
Mocap 10G 9 175 146 19.9
Furadan 10G 5 175 146 19.9
Nemacur 15G 4 185 167 10.8
Dasanit 15G 4 142 120 18.3
Dasanit 15G* 1 102 v91 12.1
Telone 6 154 107 43.9
1/ Temik, Mocap, Furadan, Nemacur and Dasanit (Except Dasanit 15G* which was
applied at 2.0 lb ai/acre in-the-row) were applied at 3.0 Ibs ai/acre in-the-row.
Telone was applied at 8.0 gallons/acre in-the-row. G=granular formulation.
2/ % increase in yield= yields from yields from
treatment minus controls x 100
yields from controls
PR 1975-5 Page 2
Table 2. Effects of nonfumigating nematicides and soil fumigants on
quality of Sebago potato tubers. Summary of seven experiments performed
Nematicidel/ Mean-Tubee~i %
Quality Rating Improvement in
Treated Control Quality2/
Temik 10G 4 2.8 5.6 50.0
Furadan 10G 7 3.0 5.3 43.4
Mocap 10G 6 2.9 5.4 46.3
Dasanit 15G 3 3.4 5.0 32.0
Nemacur 15G 2 3.5 6.2 43.5
D-D 2 3.4 5.6 39.3
Telone 3 3.4 5.1 33.3
1/ All chemicals except D-D and Telone applied at 3.0 Ib ai/acre in-the-row
Telone applied at 8.0 gallons and D-D at 10.0 gallons, per acre in-the-row.
2/ % Improvement in quality= Quality rating
of control minus
Quality rating of control
of treatment x 100
PR 1975-5 Page 3
STable 3. Effects of nonfumigating nematicides and Telone on severity
of corky ringspot disease (CRS). Results from two experiments performed
Nematicide Rate (ai/acre)l/ CRS Rating 2/
Test 1 Test 2
Temik 10G 3.0 Ib 2.3 1.5
Mocap 10G 3.0 lb 5.0 3.0
Dasanit 15G 2.0 Ib 4.7
Furadan 4F and 10G 3.0 lb 2.0 1.1
Nemacur 15G 3.0 lb 4.0 3.5
Telone 8.0 gallons 7.0
Control 4.3 3.6
1/ Furadan 10G was used in Test 2. All chemicals applied in-row.
formulation. F=flowable formulations.
2/ Corky ringspot rated on 1-10 scale (1= No tubers affected with CRS.
10= all tubers severely affected).
PR 1975-5 Page 4