TOBACCO RESISTANT TO BLACK SHANK 9 
possessing resistance to both diseases have been obtained. Similar 
results have been obtained by crossing 400 on third generation second 
backcross lines having as flue-cured parents such varieties as Virginia 
Bright Leaf, White Stem Orinoco, and Warne. None of these, 
however, is yet ready for release. 
STATUS AND DESCRIPTION OF RESISTANT STRAINS 
Many growers have only limited areas on their farms suitable for 
growing tobacco of good quality, and with these fields contaminated 
with the black shank parasite, they face the possibility of complete 
loss of the crop if ordinary flue-cured varieties are planted. In view 
of the urgent need of effective control of the disease, particularly 
under present emergency conditions, it is felt that certain of the F, 
selections from second backcrosses to Virginia Bright Leaf, White 
Stem Orinoco, and Warne possess sufficient disease resistance, yielding 
capacity, and quality and are sufficiently stable to justify their release 
to growers. The following brief descriptions will indicate the chief 
growth characteristics of these strains: 
Black Shank Resistant VBL-Strain 1 (Oxford 1)—This strain (fig. 
3, A) can hardly be distinguished from the flue-cured parent, Virginia 
Bright Leaf. The leaves are smooth, fairly thin, fine-textured, and 
about three-fifths as broad as long, with the broadest area situated 
about one-third the distance from the base of the leaf to the tip. 
They are spaced at fairly wide intervals on the stalk. This strain has 
ample spread and grows with a slight yellowish cast. It should not 
be harvested until fully mature. 
Black Shank Resistant VBL-Strain 2 (Oxford 2)—This strain is 
similar to strain 1, above, although the leaves are somewhat smaller 
and more closely spaced on the stalk. Also, they are less smooth and 
have a deeper shade of green. They appear to be shghtly thicker 
and when cured have slightly more body. 
Black Shank Resistant WSO-Strain (Oxford 3)—This strain (fig. 
3, C) has a leaf very similar to that of the flue-cured parent, White 
Stem Orinoco. The stalk is small and the leaves are widely spaced 
on the stalk. The leaves are smooth and very fine-textured and 
possess good body. They are not so large as those of the Virginia 
Bright Leaf strains. 
Black Shank Resistant W-Strain (Oxford 4).—The growth habits of 
this strain (fig. 3, B) are very similar to those of the flue-cured parent, 
Warne, the main difference being that the hybrid grows with a slightly 
lighter green color; and the cured leaf possesses somewhat less body. 
The leaves are spaced at moderate intervals on.the stalk and droop 
slightly. 
These strains are recommended for growing only on farms where 
black shank is present. In suggesting their use at this time to meet 
pressing needs it is recognized that they are in need of further improve- 
ment with respect to quality and uniformity of product. It should be 
possible by judicious selection and testing to obtain within 2 or 3 
years strains producing a leaf of high quality and resistant to both 
black shank and black root rot. : 
U.S. GOVERNMENT PRINTING OFFICE: 1943 
