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Sm.aER DN BURIIS OUT SCAB SPOTS 



Apparently little has been published about the fungicidal proper- 

 ties of Suiruner DN (DN-111). Judging, hov/ever, from its chemical relationship 

 to Elgetol, one v/ould suspect that if applied at sufficient concentration it 

 might possess some eradicative, if not perhaps even soiTie protective, proper- 

 ties against such diseases as apple scab. Recent experi^snce with this 

 material in one of the College orchards indicates that when applied at the 

 summer concentration for red mite control, it possesses considerable eradi- 

 cative properties for scab spots on Mcintosh foliage. 



In the afternoon of June 16, two I.lolntosh trees that had not been 

 sprayed previously this season received an application of DN-111 (1.4 gals, 

 in loo). Other trees in the same block wore sprayed vath the same solution 

 to which load arsenate was added at the rate of 4 lbs. in 100 gals. At the 

 time of the applications, the latter trees showed 18^i of the terminal shoots 

 with light scab infection, while the unsprayed trees had 50^o and 10% respective- 

 ly of their terminals infected. The temperature ranged from 83° to 85° F. 

 and the humidity vms high. In the early forenoon of June 19, practically 

 every scab spot on all of the sprayed trees where the leaves were thoroughly 

 wet by the sprays appeared to be burned out. Tlie leaf tissue was brown and 

 dead clear through the leaf. There was no visible injury to the leaves 

 th-^^m selves except at the scab spots. 



Based on a macroscopical examination only, the eradicant action of 

 the sprays appeared to be more uniform and complete and with less leaf injury 

 than is ordinarily obtainable with a spray of liquid lime-sulfur (2 gals, in 

 loo). Hov;ever, it is a bit early to pass judgment on the question of foliage 

 injury since less than three days had elapsed after the treatments were made. 

 If DN-111 spray at the summer concentration for red mite control should prove 

 consistent and reliable as an eradicant for scab spots on the foliage, its 

 use in scabby orchards would indeed be valuable aside from its effect on the 

 red mite population. 



— 0. C. Boyd 



MORE ON B L QSSQLI THINNING SPRAYS 



VJ'e are looking for reports from growers who tried caustic sprays 

 at blossoming time for thinning apples or other fruits. We tried this method 

 on V/ealthy, Duchess, and Mcintosh, also on several varieties of peaches, using 

 concentrations of from 1 to 3 piats of Elgetol in 100 gallons. A comparison 

 is being made of one and two applications, and times of application as rela- 

 ted to the development of the blossoms. It is too early to draw final con- 

 clusions, but some preliminary statements may bo ventured. A spray of 2 

 pints in 100 gallons took off all or nearly all the fruits on moderately 

 vigorous Mcintosh. Duchess trees were sprayed once, 2 pints in 100 gallons, 

 on either May 9, May 11, or May 12. All sprays were more or less successful. 

 Thespray on Muy 11, v/hen practically all spur flowers were open and a fev^ 

 petals were falling, gave the best results. These trees need little or no 

 further thinning. Similar treatment on VAjalthy on the same dates, when the 

 flowers v;ere less advanced, apparently show no results from the early spray 

 and only partial thinning from the medium and late sprays. 



