72 ANNUAL REPORTS OF DEPARTMENT OP AGRICULTURE, 1951 
CONTROL OF PLANT DISEASES 
Campaign Againsl W 1 1 i t « • Pine Blister Rust Continued 
Blister rust under control in nidc area 
Progress in ribes eradication by cooperating Federal, State, and 
private agencies has brought blister rust under control on more than 
half of the area in the work program. This condition was maintained 
l»\ periodic examination and removal of ribes bushes from affected 
areas and by enforcement of quarantine regulations to prevent 
replanting and subsequent escape and establishment of cultivated 
bushes in protected areas. Control of the disease has reached this 
maintenance status on all important pine plantings in Delaware, New 
Jersey, Maryland, Kentucky, Tennessee, Georg . S ith Carolina, 
Connecticut, Rhode [sland, and Massachusetts. 
Disease-control conditions were maintained around ~ [] forest-tree 
nurseries containing about 37 million white pines to provide rust- 
free planting stock. This required the removal of only 26,481 ribes 
bushes from 9,1 x .'» ;i<nv- of land, or an average of Less i ban 3 bushes an 
acre, indicating a high degree of protection. 
Experiments with fog application of light dosages of 2,4-D in a 
helicopter showed enough promise of lowering costs of ribes eradica- 
tion on some sites to warrant furt her tests. Methods of t reat ing ribes 
stems with lM-J) and 2,4,5-T dissolved in Diesel oil were improved 
as a result of mdre precise data on dosage, formulations, and equip- 
ment accessories. Studies on ribes ecology in relat ion to cutting prac- 
tices, pine regeneration, prescribed burning, and broadcast and selec- 
i ive application of herbicides were continued in cooperation with the 
Forest Service. 
Work efficiency increased by improved methods 
Improved hand and chemical methods of ribes eradication have 
increased production and efficiency in cooperative control operations. 
The one-man method of ribes eradication is dow well established in 
all regions and more work of better quality has been obtained with 
additional experience in its use. 
Ribes eradication on more than 10,000 acres of white pine land was 
contracted to individuals on a bid basis in the western white and sugar 
pine regions. AJbout 19 percent of the ribes-eradication work in the 
sugar pine region and 9 percent in the western white pine region was 
done bj contract. Where ii can be used effectively, this method is 
cheaper than rami) operations on ribes sites. Ii is not used in tin 4 
Fa i . \\ here local labor is employ ed. 
RibeS removed e>n nearly 1,400,000 aeres 
The cooperating agencies, under Bureau leadership and technical 
direction, destroyed more than L8 million ribes bushes on nearly L.400,- 
I acres of land to protect valuable white pine stands. A.bout three- 
fourthe of this work involved removal of ribes regrowth <»n partially 
protected area . Sea onal employees used on ribes eradication num- 
bered 3,430, and 63 camps were operated in remote forest areas to 
<:iii\ on the lidd work. Also, nearly 11,000 rust infected white pine 
tree in forest plantings were 3aved from destruction l»\ cutting off 
i he di ea sed part s. 
