Methods of Bacterial Plant Pathology

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PREFACE F u n g i am ong v ario u s groups of m icroorganism s a re know n to cause d estru c tiv e d iseases of crop p la n ts for th e la s t m an y y e a rs b u t it h a s been realized m uch la te r t h a t b ac te ria can also cause d estru ctiv e diseases. In In d ia, several diseases such as citru s can k er, a n g u la r le a f spot of cotton, sta lk ro t of m aize, b a c te ria l w ilt of p o tato a re know n to occur b u t it w as no t realized ab o u t th e d am ages th ese could cause. In th e 1960 s th e re w as a n epidem ic o u tb rea k of b acterial b lig h t of rice in th e e a ste rn p a rts of In d ia, p a rtic u la rly in th e s ta te of B ih ar. T h ere w as lot of h u e a n d cry am ong th e fa rm ers of B ih ar who com pelled th e g o v ernm ent to move in th e m a tte r quickly. As a re su lt, p la n t p ath o lo g ists of d ifferen t disciplines becam e very active to find ou t th e cause of th e disease. E ven foreign sc ie n tists w ere invited to in v estig ate th e m a tte r. U ltim a te ly th e J a p a n e s e sc ie n tists identified th e d isease a n d its cau sal organism w as found to be a b acteriu m a n d it w as identified as X a n th o m o n a s oryzae w hich causes b a c te ria l b lig h t of rice in J a p a n also. T his gave a g re a t fillip to th e stu d y of b ac te rial diseases in d ifferen t p a rts of India. T hese in v estig atio n s an d ch a rac te rizatio n of p athogenic b ac te ria will h av e to be done firs t in th e lab o rato ries a n d th e n ta k e n to th e fields. T he lab o rato ries d u rin g th is period w ere illequipped for bacteriological work besides u n av a ila b ility of e sse n tia l books and in p a rtic u la r by In d ian a u th o rs dealing w ith In d ia n problem s. M oreover, th e lite ra tu re av ailab le w as m ostly in th e form of p am p h lets, notes, sm all re se a rc h p ap e rs etc. and th e re w as no basic lite ra tu re th a t stu d e n ts, even re se a rc h w orkers or teac h ers could find th e n ecessary re ad in g m ateria l a t one place in a book form. W ith th is view in m ind, I sta rte d to w rite a book to fill th is gap. I hope th e book serves th e purpose for w hich it is w ritten .
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I am extrem ely th a n k fu l to D r J.M . Young, B acteriologist, DSIR, A uckland for sen d in g m e very v alu ab le re p rin ts on th e subject, w hich helped m e m uch p a rtic u la rly ab o u t th e inform ation in his articles re g ard in g re cen t tre n d s in taxonom y of phytopathogenic b acteria. I am also th a n k fu l to him for h is valu ab le com m ents on taxonom y. I am g ra te fu l to Prof. S.D. G a rre tt, U n iv ersity of C am bridge, C am bridge for sending m e th e p h o tograph of Dr. W .J. Dowson along w ith h is life history. I am th a n k fu l to Dr. J.F . B rad b u ry , CAB, Kew for his help in identification of b ac te rial species sen t to him from tim e to tim e an d for his valuable com m ents. I am also th a n k fu l to Dr. A b h ish w ar Sen, I.A.R.I., New Delhi, for his help re g a rd in g seed tre a tm e n t w ith R hizobium . I sincerely th a n k Prof. L.L. Som ani for critically going th ro u g h th e m an u scrip t. T h an k s a re due to Dr. B ab ita S ax en a for h e r help in electron m icroscopic w ork an d to Dr. A u p a ra jita for h e r assistan ce in th is work.