Indiana Plant Diseases, 1921 193 



and that 23 of these 26 fields contained southern-grown plants. The 

 source of the plants in the remaining three could not be determined. In 

 numerous instances the southern plants were a total failure and had 

 to be replaced with home-grown plants. The loss in time and labor to 

 many growlers was in itself very discouraging. The loss and incon- 

 venience to the canners who purchased southern-grown plants were 

 serious factors. In addition to the instances above mentioned, canners 

 in Delaware, Dubois, Madison, and Grant counties reported similar 

 losses in southern plants. In one case reported, three acres on one side 

 of a field were planted with Indiana plants and six acres on the other 

 side with Georgia plants and wilt was severe among the Georgia jDlants 

 while none appeared in the home-grown plants. The really alarming 

 feature of this situation is, of course, the permanent infestation of 

 more and more of our Indiana tomato soils with the wilt fungus. 



Mosaic was noted in a greenhouse in Lafayette in March and in 

 the Indianapolis hothouses in May. It was found in a market garden 

 near Vincennes on June 28, in a garden at Lafayette on July 6, and in 

 the market gardens near Indianapolis on July 12. The disease was 

 not, however, as prevalent in the market gardens at this date as in 

 the canning crop fields, but later became very general in the gardens. 

 In 30 acres of tomatoes examined near Paoli on June 29, only one mosaic 

 plant was found. Canning crop fields in Washington, Johnson, Howard, 

 Tipton, Marion, and Hancock counties were examined between June 29 

 and July 21 and mosaic was found in 55 out of 76 fields. On July 13, 

 a tomato plant with six shoots showing extreme mosaic and one shoot 

 apparently normal was found and several similar cases were noted in 

 the same field. 



Mosaic has been particularly prevalent in central Indiana and the 

 reason for this condition has been established and reported at some 

 length in another paper (24). In brief, it has been found that the mo- 

 saic disease crosses very generally from tomatoes to certain perennial 

 weeds related to the tomato and, once infected, such weeds send up dis- 

 eased shoots year after year. Four common Indiana weeds are thus 

 involved, Physalis subglabrata, P. virginiana, P. heterophylla and So- 

 lanum carolinense, and of these the first two are particularly abundant 

 in the fields of the corn belt in this state and are by far the most im- 

 portant carriers of mosaic. These weeds, as they become infected, con- 

 stitute a perennial source of infection. Mosaic has been found in abund- 

 ance on the Physalis plants in fields previously in tomatoes. As more 

 and more new fields are used for tomatoes and the perennial weed flora 

 becomes infected with mosaic, it is only a matter of time before all of 

 the tomato growing regions will become generally and permanently in- 

 fested with the disease. However, as the situation is understood at 

 present, the greatest immediate danger seems to lie in the presence of 

 mosaic weeds in and near tomato seed-beds and plant-beds, since these 

 weeds serve as early sources of mosaic infection for the tomato plants. 

 In a field survey, unmistakable evidence of the plant-bed origin of mosaic 

 was obtained. As a mosaic control measure it is very necessary that 

 tomato plant-beds be kept free from weeds and remnant tomato plants 

 all summer and that a determined effort be made to eradicate all weed 



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