THE GRAND RAPIDS TOMATO DISEASE. 



The writer received (July 27, 1909), from Grand Rapids, Michigan, diseased tomato 

 plants taken from a field of 1 1 2 acres, said to be badly affected by a new disease. 



PRELIMINARY STUDIES. 



There was no surface indication of the cause of the disease, but some of the vessels, espe- 

 cially those next to the pith, were packed full of a short bacterium which appeared to have 

 no self-motility when examined in water. It was a short rod, single or in pairs, termo-like. 

 There was very little brown stain in the wood, but yet some. In morphology it was closely 

 like Bad. solanacearum from this part of the country, i. e., a short rod with rounded ends. 



Petri-dish poured-plates were made at once from a stem showing least disease. From 

 another stem, after removing the bark, I took about 2 inches, crushed this in 10 c.c. of 

 bouillon, let stand an hour, and then inoculated with drops of this cloudy bouillon, 2 young 

 tobacco plants and 10 soft shoots of tomato. The tobaccos were young hot-house plants 

 with leaves about 2 inches wide and 3 inches long. The tomatoes were vigorous shoots on 

 two plants, standing in a garden. The presence of bacteria in the cloudy bouillon was 

 checked under the microscope before using. They were introduced by needlepricks. 



August n, i pop. Examined to-day the tomato-plants inoculated July 27 with bouillon in which 

 had been stirred up bacteria taken directly from the Grand Rapids tomatoes. 



Result. Three or four of the ten inoculated shoots show wilting leaves, but not any great number 

 on any one shoot. 



The two tobacco plants inoculated on July 27 direct from the Grand Rapids tomato shoots have 

 shown no signs of disease. 



The poured agar plates of July 27 yielded a pure culture of a yellow organism, growing in round 

 colonies. 



The plates poured on August 9 from the second sending of plants from Grand Rapids, Michigan, 

 yielded (August 17, 1909) yellow colonies closely resembling those obtained from the plates made 

 from the first plants received. The surface colonies were round, pale yellow, becoming gradually 

 deeper yellow, but not orange. They were 2 to 5 mm. in diameter and a good deal resembled Bacte- 

 rium campestre, the surface being smooth and wet-shining. The buried colonies were smaller, deeper 

 yellow, inclined to be more or less clumpy. There was no indication in the plates of the presence of 

 any white organism apparently the Grand Rapids disease is due to a yellow bacterium. This 

 infests the vascular bundles, and also rots the pith, but there is much less brown staining than in the 

 case of Bact. solanacearum. It seems also to enter above ground, the roots being free in the plants 

 examined. 



Inoculations on July 27 direct from one of the stems of the first lot were made into rapidly grow- 

 ing tomato shoots in the garden of the entomologist. One of these shoots was cut and brought in 

 to-day (Aug. 17). A few of the leaflets were wilted on three leaves and the shoot generally appeared 

 to be impaired in its growth. On cutting open the stem a great number of bacteria were found in the 

 vessels to a distance of 12 inches above the point of inoculation and 4 inches below it. In places the 

 pith was rotted. Great numbers of bacteria were present in some of the vessels. We now made in 

 the hot-house inoculations with pure cultures (subcultures from poured-plate colonies). 



Plates were poured August 23 by Miss Bryan from a diseased tomato shoot from the garden. 

 This shoot was inoculated by Dr. Smith July 27 with ooze taken directly from the first lot of diseased 

 tomatoes received from Grand Rapids, Michigan. For some days nothing appeared on the plates 

 except a few scattering colonies of intruders, but afterwards they came up plentifully with the same 

 organism that was inoculated. On September 3, 1909, the plates showed a pale yellow, smooth, 

 wet-shining, round, surface colony not unlike Bacterium campestre. The buried colonies were smaller, 

 round to broadly elliptical. The intruder was a wrinkled, raised, gummy -looking, roundish, yellow 

 colony. 



Transfers were made from one of these plates to keep the organism growing. 



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