p j a n w u f e n g. t a r i. g o v. t w % % % 40 % Pseudomonas syringae

Transcription

1 10: , , p j a n w u f e n g. t a r i. g o v. t w : Pseudomonas syringae 3-4 mm % 20 % % % % 40 % 73 % - 85 % % % % Pseudomonas syringae ( 4 ) 1999 ( 2 ) 1 mm % 1800 ( N a O C l ) 1 min ( P D A ) 1-2 KB (King et al's medium B agar) (12) ( 8, 10 ) P D A ( 4 ) P s e u d o m o n a s c a r 3 c a r 4 s y r i n g a e (6,10) 1993 ( 1 ) P D A 24 2 P D A

2 % ( M a n c o z e b 2 ) 3 3 % ( M a n c o z e b ) 4 0 % ( O x i n e - c o p p e r ) 4 0 % (Oxine-copper + copper hydroxide ) % ( P e n c o n a z o l e ) 2 5 % ( P r o c h l o r a z ) 5 0 % (Prochlorate manganese ) 7 0 % ( P r o p i n e b ) 8 0 % ( S u l f u r ) % ( T h i a b e n d a z o l e ) 5 3 % (Thiabendazole + oxine-copper ) 7 0 % ( T h i o p h a n a t e - m e t h y l ) % 1 (Thiophanate-methyl + streptomycin 19 ) 7 3 % (Zineb + basic copper 2 s u l p h a t e ) 10 ppm ppm 1000 ppm cm P D A 2 ( c a r 3 c a r 4 ) (Whatman NO.1) c f u / m l ml ( c f u / m l ) 15 ml PDA 2 2 ( 9 cm) cm ( m m ) = 3 3 ( (mm)-9 mm( ))/2 % = ( x ) (3 x ) x 100% % (7) % 73% - ( B i t e r t a n o l ) 7 5 % ( C h l o r o t h a l o n i l ) 7 7 % (Copper hydroxide ) 8 5 %, 7 4 (Copper oxychloride ) 6 3 % (Copper oxychloride + zineb + maneb 7 20 ) 7 0 % ( D i t h i a n o n 5 ) 4 0 % ( F l u s i l a z o l ) 8 0 % 0-3 ( F o s e t y l - a l u m i n i u m ) 5 % ( H e x a c o n a z o l e ) 2 % ( K a s u g a m y c i n ) % = ( X ) (3 X (Kasugamycin + Copper Oxychloride ) ) X 100% ) 8 0 % ( M a n e b ) % (Metalaxyl + copper oxychloride ) 4 0 % ( M y c l o b u t a n i l 85 % %

3 141 ( ) mm P D A K B ( S p e c r o n i c s ( Fluorescence analysis cabinet CM-10 ) ) P D A ( c f u / m l ) ( ) ( A ) ( B ) ( C ) ( D ) Fig. 1. Symptoms of the bacterial spot of carambola caused by Pseudomonas syringae. (A) the view of a seriously infested trees with few leaves on the twigs in the field; (B) necrotic spots on fruits ; (C) necrotic spots on a leaf ;(D) necrotic spots on a twig.

4 Table 1. Susceptibility of carambola varieties against P D A 4 Pseudomonas syringae strain from carambola Va r i e t y Disease index Premature leaf S u s c e p t i b i l i t y 3 (%) 1 d r o p 2 Erh lin juan chih, H S Malaysia, H S Wu peng tou fan, S 7 21 S o u r, S Tai nung No.1, S 19 ( Kuang tung, M S ) 14 Chin ran, M S Shih chan, M S % % Cheng, M S Miss, M S Cheng chui, M S % Chiao tzu tou, M R % % Nan yang, % % C h u, M R M R Wai wei, M R Wu peng tou, M R Pai se chung, M R P D A Tai pa, R Sey zen, R 1 63 % 85 % Disease severities (disease grades ) were recorded 21 days after % % two lesions per leaflet, 2 = three or more lesions per leaflet and % 40 % 3 = leaf yellow and drop, and were converted to disease index 73 % - 77 % disease grade )/ (3 x total numbers of surveyed leaflets )] x 8 ( ) 100 % ppm. Premature drop of inoculated leaves, +++: severe; ++: moderate; 2-10 mm 100 ppm 3. Disease index: HS (highly susceptible), %; S 6-17 mm 1000 ppm 13 - (susceptible), 61-80% MS (moderately susceptible), 41-60%; 22 mm MR (moderately resistant), 21-40%; R (resistant), %. 2 % 80 % ( %) (P= ) 70 % 40 % 80 % % 25 % 50 % 80 % % inoculation, based on a scale of 0 = no symptoms, 1 = one or by the formula [ ( disease grade x numbers of leaflets in that +: slight; : none. 4 ( 5, 9 Colletotrichum gloeosporioides Penzig ) 85 % % ( 9, 11) C e rcospora achyranthis S y d o w % (3) Phellinus noxius (C o r n e r) c u n n % % 9. 1 % 8. 8 % % 8. 5 %

5 143 Table 2. Effect of chemicals on the of growth of P s e u d o m o n a s s y r i n g a e from carambola on potato dextrose agar plates C h e m i c a l Inhibition zone (mm) 1 10 ppm ppm 1000 ppm Bitertanol, 28% EC Chlorothalonil, 75% WP Copper hydroxide, 77% WP Copper oxychloride, 85% WP Copper oxychloride+z i n e b +maneb, % WP Dithianon, 70% WP Flusilazol, 40% EC Fosetyl-aluminium, 80% WG Hexaconazole, 5% FP Kasugamycin, 2% L K a s u g a m y c i n +Copper Oxychloride, % WP Mancozeb, 80% WP Mancozeb, 33% FP Maneb, 80% WP M e t a l a x y l +copper oxychloride, % WP Myclobutanil, 40% WP O x i n e - c o p p e r, 40% WP O x i n e - c o p p e r +copper hydroxide, % WP Penconazole, 10.5% EC Prochloraz, 25% EC Prochlorate manganese, 50% WP Propineb, 70% WP S u l f u r, 80% WP Thiabendazole, 41.8% FP T h i a b e n d a z o l e + o x i n e - c o p p e r, % WP Thiophanate-methyl, 70% WP T h i o p h a n a t e - m e t h y l +streptomycin, % WP Zineb +basic copper sulphate, % WP C K Radius of inhibition zones of bacterial growth in paper disc a s s a y. 2. Concentration of chemicals ( 300 ) 2001 ( 5, 9 ) ( ) % % 40 % 73 % ( ) ( ) ( ) ( 8, 10 ) ( 1 ) ( 2 ( 3 ) Pseudomonas syringae ( 6, 10 ) ( 4 ) ( 2-6 ) ( 5, 8 ) ( 1 ) ( 2 ) (

6 Table 3. Efficacy of various chemicals on the management of bacterial spot of carambola caused by Pseudomonas syringae in the fields C h e m i c a l Fold of Disease index( ) D i l u t i o n I 1 I I I I I Copper oxychloride, 85% WP a a 7.3 a Thiophanate-methyl + streptomycin, 68.8% WP a 16.0 ab 9.1 a 4-4 Bordeaux mixtures 17.5 a 14.4 a 8.5 a Oxine-copper + copper hydroxide, 40% WP a 16.4 ab 8.8 a Zineb +basic copper sulphate, 73% WP a 21.1 b 12.4 b None (CK) 17.3 a 40.0 c 38.4 c 1. Investigation times. I: prior to the first chemical application; II: prior to the third chemical application; III: 7 days after the 4 t h ( l a s t ) chemical application. Chemicals were applied every 7 days. 2. Means in each row followed by the same letter are not significantly different at p=0.01 according to Duncan's multiple range tests. 2-6 ) ( )... ( 3 ) : ( 34 ) :215. ( ) Pseudomonas syringae 16 ( 1 ): : ( ) Hsieh, W. H., and Goh, T. K C e rcospora a n d Similar Fungi from Taiwan. Maw Chang book company Taipei. 376 pp Phellinus noxius 1 2. Schaad, N. W Laboratory Guide for Identification. 8 : of Plant Pathogenic Bacteria. 2 n d ed. APS press. USA. 164pp.

7 145 A B S T R A C T Tsai, J. N. 1, Ann. P. J., 1, 4 Lin, C. Y., 1 Wu, Y. F., 2 and Peng, S. J Occurrence, variety resistance and chemical control of bacterial spot of carambola. Plant Pathol. Bull. 10: ( 1. Department of Plant P a t h o l o g y. Taiwan Agricultural Research Institute, Wu-feng 413, Taichung, Taiwan; 2. Kaohsiung Branch Station, Bureau o animal and Plant Health Inspection and Quarantine, COA; 3. Miaoli District Agricultural Improvement station, Miaoli, Taiwan; 4. Corresponding author, pjann@wufeng.tari.gov.tw; Fax: ) Bacterial spot of carambola (starfruit, Av e rrhoa carambola) caused by Pseudomonas syringae was first found at Miaoli, Cholan in 1987 in Taiwan. The bacterium attacked leaves, twigs and fruits, and induced symptoms as red-brown spots about 3-4 mm in diameter on infected tissues. The necrotic spots on leaves were surrounded with yellow halo. The infected leaves turned yellowing and were premature falling, whereas most of the fruits infected in the early stage were also premature dropping, the remains grew malformed. This new bacterial disease caused serious economic losses to farmers. Our results showed that the bacterial disease only occurred in the central Taiwan at present, including Cholan of Miaoli, Tu n g s h i h, Shihkang, and Hsinshe of Taichung, Kuohsing of Nantou and Yuanlin of Changhua Counties. Artificial inoculation demonstrated that all the 19 tested carambola varieties were infected by the pathogen. Among the tested varieties, Erh-lin-juan-chih and Malaysia were the most susceptible to the bacterium. Almost all the inoculated leaves of the two varieties were fallen with the disease incidences were 91.7 and 83.3%, r e s p e c t i v e l y. However, Tai- pa and Sey-zen were slightly infected with disease incidences were both 18.3% and none of the inoculated leaves fell, were considered to be resistant to the bacterium. The results of chemicals test and field trials indicated that 85% copper oxychloride, 68.8% thiophanatemethyl+streptomycin, 4-4 Bordeaux mixtures, 40% oxine-copper + copper-hydroxide, and 73% zineb+basic copper sulphate were effectively inhibit the bacterial growth on PDA as well as decrease the disease in the f i e l d s. Key words : Carambola (Av e rrhoa carambola), Pseudomonas syringae, resistance, chemical control

8