2 BULLETIN 1118, U. S. DEPARTMENT OF AGRICULTURE. 
is important. It is not uniformly serious throughout the citrus- 
growing sections of the Gulf States, but in certain well-defined 
localities scab is of the greatest importance. 
The damage done to leaves on bearing trees is more unsightly 
than harmful (Pis. I and II; PL III, Fig. 2). There is no tangible 
evidence to show that the functioning power of moderately affected 
leaves is seriously impaired. 
In orchards where a large proportion of scab has recently developed, 
especially where the infection is serious enough to cause a marked 
distortion of the fruit (PL III, Fig. 1), the dropping of fruit recently 
set is considerably greater than where scab does not occur in serious 
proportions. A large percentage of this dropped fruit is distorted 
by scab. In addition to the rather intangible financial loss brought 
about by the abnormal early drop of green fruit due to scab infec- 
tion, a more tangible loss is occasioned by scabby fruit reaching 
maturity. A badly blemished fruit is a cull; a slightly blemished 
fruit has to be sold by the producer at a discount of at least 50 cents 
per box in years of fair prices. An average estimate made by con- 
servative business men familiar with the citrus industry covering 
the scab losses to citrus growers in Florida is about 1,000,000 boxes 
infected annually. With the production of citrus fruits in Florida 
increasing rapidly, the average annual losses from scab are likely to 
increase. Under the most favorable circumstances the cost of pro- 
duction of grapefruit, kid-glove oranges, tangelos, and lemons of first 
quality is greatly increased in districts where scab is a serious factor 
and has to be controlled by sprays. 
The damage done to groves before they come into bearing is con- 
siderable, but usually not sufficiently great to render control measures 
imperative. Nevertheless, a reasonable investment in protective 
measures may be used to financial advantage. 
Scab is the only parasitic fungous disease of consequence occurring 
in the citrus nursery. There it is extremely serious. It produces a 
very marked stunting effect upon seedling stocks for budding (PL IV), 
frequently reducing the growth by about 40 to 50 per cent. Where 
citrus scab is held under control vigorous seedlings are sufficiently 
large to be budded after having been transplanted to nursery rows 
for a growing season. Where the disease occurs in quantity and is 
not held in check by treatment, seedlings may require from 2\ to 3 
or more years to make sufficient growth to be budded. This disease 
is of such serious consequence to rough-lemon and sour-orange nursery 
stock that nurserymen are in search of a desirable stock immune to 
citrus scab. Grapefruit leaves are most susceptible to infection as 
they begin to expand. They become entirely resistant to infection 
by the time they reach a half inch in width. Fruit is susceptible 
until it is about three-fourths of an inch in diameter. 
