EXPERIMENT STATION BULLETINS. 455 



fungicide, that would remain on the fruit after it was harvested, without 

 staining or otherwise being apparent, would be very beneficial. Sulphur dust 

 seemed to be the material that best fulfilled these particular requirements so 

 was used in an experimental way with the results herein reported. 



EXPERIMENTS IN 1920. 



Experiment at South Haven. The first work of this nature was conducted 

 near South Haven on the H. E. Hawley farm in 1920. 



The variety was Lombard. The trees were 10 years old and in full bearing. 

 Many of the trees bore quite heavy crops and none of them were thinned. 

 The control of brown rot before harvesting under such conditions was more 

 difficult than if the trees had been properly thinned. 



Materials Used. Two materials, were used in the experiment which were 

 as follows: 



1. Lime-sulphur solution, 13^-50. Lead arsenate was used in combination 

 at the rate of 1J4: pounds in 50 gallons. 



2. Sulphur *dust, 90-10 mixture. Sulphur alone was used for the later 

 applications. 



The orchard was divided into two large plots for each of the materials and 

 one small plot which was left untreated as a check. The sprayed plot con- 

 tained about 60 trees and the dusted plot about 95 trees. The check plot 

 which contained eight trees was located in a corner of the sprayed plot as 

 far as possible from the dusted plots so as not to be affected by any drifting 

 dust. 



Applications. The dusting materials were all applied with a large power 

 duster and the work was usually done in the morning or evening but thete 

 was frequently some wind blowing so that conditions were not ideal fpr 

 dusting. The spraying was done with a power sprayer which usually maiiii- 

 tained a satisfactory pressure. A spray gun was used. Applications were 

 made at the periods and with the materials indicated below. 



1st. Just before blossoms opened. Both plots were treated. 

 2nd. Just after blossoms fell. Both plots were treated. i 



3rd. Two weeks after second. Both plots were treated. : 



4th. July 9. Sulphur dust plot treated with 90-10 mixture from one 



side of trees. : 



5th. About one month before harvest. Both plots were treated but ilo 



lead arsenate was used. , , i 



6th. One week before harvest. Sulphur dust plot was treated with straight 



sulphur. \ 



RESULTS. I 



' > ■ 

 Control of brown rot before harvest. The following note was made on 

 June 21, "All trees have a few plums affected with rot, the infection apparently 

 having been made in every case through curculio stings. The rot does not 

 seem to be spreading and is found uniformly on dusted, sprayed and check 

 trees." This early infection did not spread at the time but was probably 

 responsible, in part, for an occasional rotted cluster later in the season. 

 As stated earlier, the fruit was- not thinned and it would be difficult to stop 

 the spread of brown rot in a cluster of fruit if one had become infected through 

 a curculio sting. 



