OREGON
June 1965
ORNAMENTAL AND
Vol.9, Issue 2
NURSERY DIGEST Page 5
Ira W. Deep
Department of Botany and
Plant Pathology
Oregon State University
Corvallis, OR
PREPLANTING TREATMENTS FOR CONTROL OF CROWN GALL
In Volume 7, Number 4, of the Oregon Ornamental and Nursery Digest a report entitled "Four
Bactericides Tested for Crown Gall Control'' was made. These materials have been retested
along with four others in an attempt to find a chemical which controls both crown gall and black
mold and which is safer to use than Semesan Bel, the material recommended at present.
Nine hundred Mazzard cherry seedlings were root pruned, injured with a file in five places on
each root, and dipped in a dense suspension of Agrobacterium tumefaciens. One hundred trees
were selected as the inoculated control, and the others in lots of 100 were given treatments as
indicated in Table 1. One hundred uninoculated trees were included to determine the amount of
incipient infection, that is, trees already infected but showing no symptoms when the experiment
was set up. The 100 trees used for each treatment were divided into groups of 25 and planted in
the field in four randomized blocks.
Four of the materials tested are similar to Semesan Bel in that they are organic mercury
compounds. Of these, Phenyl Mercury Acetate and Puratized Agricultural Spray were severely
phytotoxic. New Improved Ceresan was slightly phytotoxic and was much less effective in
control of crown gall than Semesan Bel. Morton Soil Drench was not phytotoxic and showed
some effectiveness in control of crown gall. It would be worthwhile to retest this material against
a lower level of inoculum since the material is easy to use, controls black mold, and appears to
be non-phytotoxic. Perhaps it would control crown gall in a natural situation where the inoculum
level would tend to be lower.
Semesan Bel provides excellent protection against infection caused by the crown gall bacterium
through wounds created when trees are transplanted. In this test, the level of infection after
treatment with Semesan Bel was no more than that of the uninoculated control, which
demonstrates incipient infection. The danger of phytotoxicity is shown by the moderate
reduction in stand following the treatment. Therefore, a lower dosage (5 pounds per 100 gallons)
is recommended where special danger of a toxic reaction exists, as when trees are not planted
immediately following treatment. There is no material available at the present time which
incorporates the effectiveness of Semesan Bel with absolute safety of use.
Table 1. Effectiveness of preplanting treatments in controlling crown gall
Pla nts
Treatment
Dowco 184 ⅔ pound/100 gallons ----------Semesan Bel 10 pounds/100 gallons -------Morton Soil Drench 1 ¼pounds/100 gallons-Nurelle 4 liters/100 gallons -----N. I. Ceresan 1 1/10 pounds/100 gallons---Phenyl Mercury Acetate ½ gallon/100 gallons-Puratized Agricultural Spray 1 gallon/100
gallons ----------------------------------Agri-mycin 500 (soak for 5 minutes)
3 pounds/ 100 gallons-----------------Inoculated control -----------------------------Uninoculated control ---------- ---------
Stand
Gall
%
94
76
90
78
67
9
%
97.9
6.6
55.6
71.8
47.8
22.2
14
14
0
68
10
93
7
2
90
78
95
97
87.2
97.9
72
Without
gall
No.
2
71
40
22
35
7
0
With
gall
No.
92
5
50
56
32
2
Galls per
infected
plant
Oregon Ornamental and Nursery Digest was published from 1957 to 1975 by the Agricultural Experiment Station,
Oregon State University, Corvallis.
Pesticide Use - Due to constantly changing laws and regulations, no liability for the suggested use of chemicals in
this reprint is assumed. Pesticides should be applied according to label directions on the pesticide container.
Permission to Reprint material appearing in the Oregon Ornamental and Nursery Digest is granted with the request
that you credit the source: Oregon Ornamental and Nursery Digest, date, volume, issue, page numbers. Do not
excerpt or reprint in such a manner as to imply the author's endorsement or criticism of a product or concept.
Nondiscrimination - The information in the Oregon Ornamental and Nursery Digest is provided with the
understanding that no discrimination is intended and that listing of commercial products implies no endorsement by
the authors. Criticism of products or equipment is neither intended nor implied.
Avg. No.
3.8
1.2
1.7
1.9
1.6
1.0
--1.9
4.2
1.1