Fusarium solani (Mart.) Appel &amp; Wr. was isolated from the roots of shisham (Dalbergia sissoo Roxb.) plants of 6&ndash;30 years age, showing symptoms of wilt disease at different stages. In vitro toxicity assays with three fungicides revealed that Benomyl is the most effective in controlling mycelial growth of F. solani followed by Ridomil Gold while Aliette had insignificant effect. Field study showed that application of 50 liters of 200 ppm Benomyl can effectively recover 6‑8 years old wilting shisham plants

Rukhsana Bajwa, Arshad Javaid, J.H. Mirza and Naureen Akhtar

UNIVERSITY OF THE PUNJAB

Mycopath (2003) 1(2): 111-113 Chemical control of wilt in  Shisham (Dalbergia sissoo Roxb.)  Rukhsana Bajwa*, Arshad Javaid**, J.H. Mirza* and Naureen Akhtar*  *Department of Mycology & Plant Pathology and **Department of Botany, University of the Punjab, Quaid-e-Azam Campus, Lahore 54590, Pakistan  Abstract Fusarium solani (Mart.) Appel & Wr. was isolated from the roots of shisham (Dalbergia sissoo Roxb.) plants of 6–30 years age, showing symptoms of wilt disease at different stages. In vitro toxicity assays with three fungicides revealed that Benomyl is the most effective in controlling mycelial growth of F. solani followed by Ridomil Gold while Aliette had insignificant effect. Field study showed that application of 50 liters of 200 ppm Benomyl can effectively recover 6-8 years old wilting shisham plants.  Introduction  Shisham is an important tree species of great economic importance in the sub-continent. This precious tree has been inflicted with dieback and wilt diseases in the recent years and the incidence is also reported in Tarai tract of Nepal, believed to be its home (Bajwa et al., 2003). The characteristic symptoms of shisham wilt are yellowing and death of leaves in acropetal succession up the tree, as a result the whole tree appears yellow. In advance stages the affected trees show signs of wilting, the leaf shed rendering the branches bare, and ultimately plants die within a few months. Older trees are usually found to be more prone to mortality. The outer sapwood shows characteristic pink to reddish stain. Though it is restricted to outer sapwood, it sometimes penetrates in the inner sapwood, the heartwood is not discoloured. The stain progresses along the outer sapwood of the root to the stem and in later stages of wilting it extends up the stem to about 3-5 m from the ground (Baksha and Basak, 2000). Wilting is more serious and damaging than die back because it results in a rapid mortality of the infected trees.  The objective of this study was to isolate and identify the causal agent of wilt disease and to evaluate some fungicides for prospective control of the causal organism.  Materials and Methods Isolation of the pathogen  Root samples of 10 shisham plants of different ages (6-30 years) and at different stages of wilting, were collected from Quaid-e-Azam Campus. University of the Punjab Lahore, Pakistan during September-November 2003. The root specimens were cut into small pieces and surface disinfected by immersing in 1% sodium hypochlorite solution for one minute and then rinsed thrice in sterilized water. The surface sterilized root pieces were placed on to the malt extract agar (MEA), potato dextrose agar (PDA), Czapek’s dox agar and corn meal agar media in petriplates and incubated at 25 C. After 8 days the fungal isolates appearing on the root pieces were identified and transferred to PDA slants for purification.  In vitro chemical control of F. solani  The in vitro toxicity of three fungicides viz. Ridomil Gold, Benomyl and Aliette were tested against F. solani  by the poisoned food technique (Nene and Thapliyal, 1979). Each fungicide was mixed separately in autoclaved melted PDA medium to obtain required concentration i.e., 10, 20, 30, 40 and 50 ppm. Twenty ml of poisoned melted PDA medium was poured into each sterilized plate and allowed to solidify. PDA medium without fungicides served as control. After solidification of medium, 3 mm agar plugs of the fungus on PDA were transferred in the center of the plates. Each treatment was replicated thrice. All the plates were incubated at 25 2 C. Growth inhibition rate was recorded after 8 days of incubation. Percent inhibition in fungal growth was calculated according to Vincent (1957). Data were analyzed by applying t-test.  In vivo chemical control of shisham wilt  The fungicide (Benomyl) found most effective in inhibiting the mycelial growth of F. solani in poisoned food technique was further evaluated in field for the control of shisham wilt by soil drenching with fungicidal solution of 200 ppm concentration. Three shisham plants of 6-8 years old, showing clear symptoms of wilt disease were selected in Punjab University, Lahore. Fifty litres of 200 ppm suspension of Benomyl were drenched in the soil around each selected tree. The  Control of Shisham wilt 111 Mycopath (2003), 1(2): 111-113 disease incidence was recorded 45 days after treatment.  Results and Discussion  The wilt disease was most common during the months of September -.November In India and Bangladesh the disease manifests during humid months from July to September (Sharma et al., 2000; Baksha and Basak, 2000). The affected plants show characteristic symptoms of disease i.e., yellowing and death of leaves in acropetal succession up the tree and eventually the entire tree appeared chloriotic (Sharma et al., 2000). The roots of the diseased plants were not different from healthy ones in newly diseased plants.     Fusarium solani was isolated from roots of all the infected trees. The other fungal species, which were isolated in low percentage were Aspergillus fumigatus, Fusarium sp., Curvularia sp. Sclerotium sp. and Trichoderma sp. (Fig. 1). Fusarium solani seems to be the possible cause of wilting as it was found in roots of all the infected trees in very high percentage. Shakir et al. (1999) also isolated F. solani from diseased roots and assumed this organism to be the cause of shisham decline. Similar observations have also been reported from Bengladesh, Nepal and India during the last few years. Baksha and Basak (2000) have reported a wide spread mortality of shisham trees of varying ages in Bangladesh and assumed that F. solani and shothole borer may be the cause of disease. Earlier, Bakshi (1957) also isolated F. solani from diseased shisham plants. The fungal hyphae and jelly like substances plug the vessels resulting in wilt symptoms (Bakshi and Singh, 1959). According to Davis et al. (1953) wilt is generally the result of Fusarium attack at the roots or even lower portions of stem where its growth interferes with the conduction of water and excreted toxins of the nature of conjugated phenols. According to some workers, Fusarium oxysporum is the cause of shisham wilt (Gill et al., 2001). Some people confuse the wilt with dieback. Dieback is entirely different disease characterized with thinning of leaves and crown, drying up of the ends of branches, table topped condition and stag-headness in extreme conditions (Khan, 2000). Dieback is caused by Phytophthora cinnamomi (Gill et al., 2001).  Among the three fungicides evaluated against F. solani in in vitro, Benomyl was found to be highly effective causing a significant reduction in mycelial growth of the test fungus even in very low concentration of 10 ppm. Ridomil was effective in higher concentration while Aliette failed to alter the growth of this fungus significantly even at 50 ppm concentration level (Fig. 2). Some other fungicides such as Vitavax, Dithane M-45, Bavistin and Benlate are also known to have significant suppressive effect on growth of F. solani (Ahmad et al., 1996). Benomyl, the most effective fungicide in in vitro trial was also proved very effective in in vivo experiment. All the three shisham plants, which were likely to be dead by wilting during next few weeks, managed to recover themselves from disease after treatment with Benomyl. The treatment with this fungicide may prove highly beneficial to save the shisham trees from the menace of wilting. However, there is need to study the effectiveness of this fungicide against the wilt attack in older trees. A benomyl derived fungus toxicant MBC (Methyl-2-benzi midazol carbamate) is also known to be effective against wilting. It is a stable fungicide suitable for injection into the trees (Mcwain and Gregory, 1973).       0102030405060Percentage occurrenceFusarium solani Aspergillus fumigatusFusarium sp. Curvularia sp.Sclerotium sp. Trichoderma sp.Fig. 1: Percentage occurrence of different fungi isolated from wilting shisham trees.  112 R Bajwa et al. Mycopath (2003), 1(2): 111-113      References Ahmad M, Khan MA, Ahmad F, Khan SM, 1996. Effectiveness of some fungicides on the colony growth of Fusarium oxysporum and F. solani associated with potato wilt. Pak. J. Phytopathol., 8: 159-161. Bajwa R, Javaid A, Shah MBM, 2003. Extent of shisham decline in Lahore, Sialkot, Gujranwala and Sergodha districts, Mycopath, 1: 1-6. Baksha MW, Basak AC, 2000. Mortality of sissoo in Bengladesh. In: Proceedings of the Sub-Regional Seminar on Dieback of Sissoo in Katmandu, Nepal, 25-28, April, 2000, pp.1-4. Bakshi BK, 1957. Wilt disease of shisham II Behavior of Fusarium solani, the wilt organism in the soil. Indian Forester 81: 276-281. Bakshi, BK, Singh AC, 1959. Root disease of shisham (Dalbergia sissoo). VIII. Inoculation study on wilt. Indian Forester, 85: 415-421. Davis D, Qaggoner PE, Diamond AE, 1953. Conjugated phenals in the Fusarium wilt syndrome. Nature, Lond. 172: 95. Gill MA; Ahmad I, Khan AU, Khan AU, Khan M, 2001. Phytophthora cinnamomi. A cause of shisham decline in Punjab, Pakistan. In: Proceedings of 3rd National Conference of Plant Pathology, October, 1-3, 2001, NARC, Islamabad, pp. 33-37. Khan MH, 2000. Shisham die-back in Pakistan and remedial measures. In: Proceedings of the Sub-Regional Seminar on Dieback of Sissoo in Katmandu, Nepal, 25-28, April, 2001. pp. 45-50. Mcwain P, Gregory GFA, 1973. Benomyl derived fungitoxicant for tree wilt disease control. USDA For. Serv. Res. Note, N.E. Forest Expt. Sta. No. 162. RPP. 53, 2: 689 Abst. Nene HL, Thakliyar PN, 1979. Fungicides in plant disease control. Oxford and IBH Publishing company, New Delhi, pp.507. Shakir AS, Khan SM and Ahmad R, 1999. First report on shisham decline in Pakistan. Pak. J. Phytopathol, 11: 106. Sharma MK, Singal RM, Pokhriyal TC, 2000. Dalbergia sissoo in India. In: Proceedings of the Sub-Regional Seminar on Dieback of Sissoo in Katmandu, Nepal, 25-28 April, 2000. pp. 5-17. Vincent JM, 1957. Distribution of fungal hyphae in the presence of certain inhibitors. Nature, 159: 850.   0102030405060708090100Aliet Benomyl RhidomilGrowth inhibition over control (%)10 ppm 20 ppm 30 ppm 40 ppm 50 ppm  *** ***** ******* ******Fig. 2: Percentage reduction in  in vitro Fusarium solani growth due to three fungicides as compared to control.    *, **, ***, show significant difference from control at 5, 1 and 0.1 % level of significance as determined by t-test. 

Chemical control of wilt in  Shisham (Dalbergia sissoo Roxb.)

http://journals.pu.edu.pk/journals/index.php/mycopath/article/download/5586/2621

Chemical control of wilt in Shisham (Dalbergia sissoo Roxb.)

Abstract

Similar works

Full text

Available Versions

UNIVERSITY OF THE PUNJAB