Various aspects of Phytophthora cactorum collar-rot of apple trees in the Netherlands

1955 ◽  
Vol 61 (1) ◽  
pp. 122-129 ◽  
Author(s):  
I. W. Buddenhagen
Keyword(s):  
The Netherlands ◽  
Phytophthora Cactorum ◽  
Apple Trees ◽  
Collar Rot

scholarly journals First Report of Root and Collar Rot by Sclerotium rolfsii on Apple Trees in Italy

Plant Disease ◽  
1999 ◽  
Vol 83 (7) ◽  
pp. 695-695
Author(s):  
L. Corazza ◽  
A. Belisario ◽  
E. Forti
Keyword(s):  
Apple Tree ◽  
Sclerotium Rolfsii ◽  
Apple Trees ◽  
Collar Rot ◽  
Athelia Rolfsii ◽  
Leaf Chlorosis ◽  
General Decline ◽  
Summer Temperatures ◽  
Ground Plate ◽  
Mycelial Strands

Sclerotium rolfsii Sacc. (teleomorph Athelia rolfsii (Curzi) Tu & Kimbrough) is a polyphagous, soilborne plant pathogen. In summer 1998, a sudden death of 2-year-old apple trees (Malus domestica Borkh.) cv. Royal Gala grafted on M9 rootstock was observed in an orchard near Rome, Italy. Symptoms were stunted vegetation, leaf chlorosis, and root and collar rot. A fungus identified as S. rolfsii was observed producing sclerotia and whitish mycelial strands on root and collar bark. Isolations from roots and at the margin of subcortical necrosis on the collar consistently yielded S. rolfsii colonies on potato dextrose agar (PDA); sclerotia developed within 7 days. Koch's postulates were fulfilled by inoculating 10 1-year-old apple tree cv. M9 rootstocks, grown in 3.5-liter pots, with an S. rolfsii isolate grown for 1 week on PDA at 25°C. One ground plate per plant was used, placed around collar and main roots. Five control plants were treated with PDA only. Rootstocks were kept in the greenhouse at 26 ± 2°C. Within 2 months, 70% of inoculated plants died, with marked necrosis girdling the collar. The other inoculated plants showed a general decline, with widespread necrosis on collars and main roots. Control plants remained healthy. S. rolfsii was reisolated from collars and roots of symptomatic plants. S. rolfsii has been recorded on apple trees in the U.S., India, China, and Israel. In Italy, it is destructive on several crops, and was recently recorded on walnut (1). This first outbreak of S. rolfsii on apple in Italy may have been favored by exceptionally warm late spring and summer temperatures. Reference: (1) A. Belisario and L. Corazza. Plant Dis. 80:824, 1996.

scholarly journals Fungal pathogens associated with crown and collar rot of apple trees in southern Syria

2017 ◽  
Vol 109 (1) ◽  
pp. 103
Author(s):  
Walid Ghazi Naffaa ◽  
Abeer Rashid
Keyword(s):  
Root Rot ◽  
Fungal Pathogens ◽  
Disease Incidence ◽  
Apple Trees ◽  
Disease Symptoms ◽  
Collar Rot ◽  
Infected Tree ◽  
Brown Discoloration ◽  
Infected Area ◽  
Pale Green

<p>Crown and collar rot of apple trees is a destructive and widespread disease in most areas of the world. Surveys have been done to describe disease symptoms, estimate the disease incidence, and identify the pathogens associated with this disease in southern Syria. Disease incidence was 0.08 – 10 % in most studied sites, only in Alroom location it was up to 14.7 % in 2014 and 17.8 % in 2015, with average of 11.8 %. Symptoms included small pale green leaves, sparse foliage, and a reddish-brown discoloration of inner bark of the infected area at the base of infected tree. The isolated fungi belonged to genera and form genera <em>Phytophthora</em>, <em>Rosellinia</em>, <em>Rhizoctonia</em>, <em>Phialophora</em>, <em>Acremonium</em>, <em>Pestalotiopsis</em>, <em>Cylindrocarpon</em> and <em>Verticillium</em>.<em> Phytophthora </em>was isolated from all infected trees, and was the most frequent pathogen (53.7 % of total isolates). <em>Phytophthora</em> isolates recovered from crown cankers of apple were identified as <em>P. cactorum </em>(91.5 %) and <em>P. cambivora</em> (8.5 %). The results of this study are the first report of crown and collar root rot of apple in Syria.</p>

scholarly journals Susceptibility of apple cultivars to collar rot (Phytophthora cactorum Leb. et Cohn. Schroet.)

2013 ◽  
Vol 39 (1) ◽  
pp. 5-13
Author(s):  
Zbigniew Borecki
Keyword(s):  
Laboratory Test ◽  
Field Experiment ◽  
Apple Tree ◽  
Phytophthora Cactorum ◽  
Collar Rot ◽  
Dormant Stage ◽  
Methods Of Evaluation ◽  
Apple Cultivars ◽  
End Stage ◽  
High Degree

The susceptibility of 16 apple cultivars to collar rot caused by the fungus <i>Phytophthora cactorum</i> was tested. Three methods of evaluation were applied: a laboratory test, a greenhouse experiment and a field experiment. Two cultivars were very sensitive: 'Discovery' and 'Hibernal'. The next susceptibility group comprised the cultivars: 'Gloster', 'Florina', 'Liberty', 'Julyred', 'Paulared' and 'Jonnee'. Moderately susceptible were: 'Šampion', 'Nova Easygro', 'Jonagold' and 'Quinte'. Least susceptible were: 'Summerred', 'Nüred', 'Jonamac' and 'Spartan'. Not one of the tested cultivars was completely resistant to infection with <i>Phytophthora cactorum</i>. A high degree of correlation was noted between the results obtained in the greenhouse, in the field and in the laboratory test on annual shoots cut off at the dormant stage of the trees. Much less reliable results were obtained in the laboratory test on apple-tree shoots cut in September in the end stage of vegetation of the trees.

scholarly journals Response to Artificial Infection by Phytophthora cactorum of Four Apple Scion Cultivars on Three Rootstock

HortScience ◽  
1993 ◽  
Vol 28 (7) ◽  
pp. 717-718 ◽  
Author(s):  
R.S. Utkhede ◽  
E.M. Smith
Keyword(s):  
Field Experiment ◽  
Malus Domestica ◽  
Crown Rot ◽  
Phytophthora Cactorum ◽  
Artificial Infection ◽  
Apple Trees ◽  
Golden Delicious ◽  
Scion Cultivar

A 10-year field experiment was conducted on 20-year-old apple trees (Malus domestica Borkh.) inoculated with Phytophthora cactorum (Leb. & Cohn) Schroet. to study the influence of the scion cultivar on rootstock susceptibility. The rootstock MM.111 was less susceptible to P. cactorum than M.7 when `Golden Delicious' was the scion, but there were no differences when `Delicious', `Haroldred Delicious', or `McIntosh' were the scions. Similarly, the rootstock M.26 was less susceptible than M.7 when `McIntosh' was the scion, but there were no differences when `Delicious', `Haroldred Delicious', or `Golden Delicious' were the scions. These results suggest that the influence of scions on rootstock susceptibility to P. cactorum crown rot is variable.

COLLAR ROT OF APPLE TREES IN ESSEX

1953 ◽  
Vol 2 (3) ◽  
pp. 85-86 ◽  
Author(s):  
H. C. Smith
Keyword(s):  
Apple Trees ◽  
Collar Rot
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