CHE REFERENCE LIBRARY - Pole Shift Survival Information

198 7’IlE NURSERY-MANTJA I,
certain dcgrce, in cbcmtrolling apple mildew, but the addition
of 3 pounds of iron sulfate makes a more ctfec,tive mixture.
l)usting with a mixture of 90 parts sulfur and 10 parts powdered
arsenat.c of lead also has proved satisfactory in checking the
mildew.
In some seiW2ns tile mildew is more prevalent than in other
years, aiid when the disease is sbundant an efl’ort should bc
riide to keep its much as possible of the new
growth covered with the fungicide. The first
application should be made soon after the seedlings
have developed the first new leaves.
Three or four subsequent treatments should be
made at. intervals of two to three weeks.
YEI,LO~WAL~ I~SEA~+E OF CI~RI~T mn I'Lm.
- - The yellow-ieaf may be very destructive to
nurser) trees when weather conditions are
FIG. A ‘q,3. y(+ fa\-orable. Mazzard cherry seedlings arc exlow-leaf
discasu of ceetlingly susceptible and often badly defoliclwrry.
ated. i\Iahaleh cherry seedlings are commonly
afleeted, while myrobalan plum seedlings show a considerable
degree of resistaiicc. The sweet and sour varieties of cherry
and the European varieties of plum are more susceptible to the
disease than thtb .Japanese plum varieties.
Ihsr riptiob. - The disease appears on the cherry foliage as
dark red sp( )t. c; , th:rt, ma). he abundant on the leaves (Fig. XS> .
Tn the ad\xiicecl stages of the disea,se, a yellowing of the affected
foliage may occur and the leaves fall premat.urely. On the
plum foliage the disez;e is conspicuous because of the shothole
appe:rran[*e of the leaves caused by the d.ropping out of
the c*irc&r areas of affected tissue. The same yellowing
sometimes appears on diseased plum leaves but never so abundantly
as on sweet cherry foliage.
Cause. - The yellow-leaf disease on cherry is caused by the