Dieback of Apple Tree by Major Soil Borne Diseases in Chungbuk Province from 2013 to 2015

Abstract

Recently, severe dieback of apple tree has occurred in the apple orchards of Chungbuk province. Dieback rate and its casual agents have been investigated on the Chungbuk province apple orchards in 2013-2015. Out of 29,265 apple trees in the 27 orchards throughout Chungbuk province, 4,000 apple trees (13.7%) showed dieback symptoms. The causes of dieback were Phytophthora rot (50.4%), violet root rot by Helicobasidium sp. (27.1%), rodents (10%), white root rot by Rosellinia sp. (6.3%), and freezing injury (6.3%). Compared to previous reports published in 1995 and 2006, Phytophthora rot was the most dominant disease, which is thought to be due to high temperature during growing season and the increase of lowland cultivation. Results of this study will be useful to establish of the management strategy of apple tree dieback that has been increased recently.

Dieback Reality of Apple Trees Resulting from Soil-Borne Fungal Pathogens in South Korea from 2016 to 2019

“…In apple trees, Phytophthora cactorum causes the rot of root, crown, and stem. Also, Helicobasidium mompa and Rosellinia necatrix results in violet root rot and white root rot, respectively (Lee et al, 2016;Rural Development Administration, National Institute of Agricultural Science and Technology, 1993;The Korean Society of Plant Pathology, 2009).…”

“…The symptoms caused by soil-borne diseases induce the reduction of the number of leaves and leaf area with the increase of vacant branches due to poor growth and fruit setting, and finally result in dieback (Lee et al, 1995;Lee et al, 2009;Lee et al, 2016). These symptoms are likely to be confused with physiological disorders, which make it difficult to diagnose the causes quickly and accurately (Lee et al, 1995).…”

“…These symptoms are likely to be confused with physiological disorders, which make it difficult to diagnose the causes quickly and accurately (Lee et al, 1995). Nonetheless, Lee et al (2016) reported a method to diagnose the causes of dieback resulting from soil-borne diseases at apple orchards.…”

Effect on Colony Growth Inhibition of Soil-Borne Fungal Pathogens by Available Chlorine Content in Sodium Hypochlorite

“…Recent changes in climate and cultivation environment have led to the problem of apple tree dieback caused by soil-borne diseases, which causes economic losses ( Lee et al, 2016 ). The major soil-borne diseases reported in Korea are Phytophthora root rot by Phytophthora cactorum , violet root rot by Helicobasidium mompa , and white root rot by Rosellinia necatrix ( KSPP, 2009 ; Lee et al, 2006 ; RDA, 1993 ).…”

“…The apple trees infected with these diseases show remarkably weak leaf growth, poor growth of shoots, early leaf yellowing and abscission, and reduction of fruit yield with low quality. In the case of severe damage, the entire trees become dieback within 2–3 years, and the possibility of re-occurrence is high even after supplementary planting, and eventually it is easy to reach the disused orchards ( Kim et al, 1995 ; Lee et al, 1995 ; Lee, 2002 ; Lee et al, 2016 ).…”