48 CALIFORNIA CITRUS CULTURE. 
placed under the trees, and to a lesser degree a cover crop, helps to keep 
the spores from reaching the fruit. The usual strength of the bluestone 
water for brown rot is one and one half pounds to one thousand gallons. 
This fungus, as we have seen, causes one kind of gum disease of 
lemon, see page 44. 
Cottony Mold or White Rot (Sclerotinia libertiana). 
This is much like the brown rot, except that it coats the fruit with 
white. It attacks and often kills the twigs a foot or two from the end. 
In this mold develop black bodies (sclerotia), another stage in the 
erowth of the fungus. This fungus also develops in the soil, and is 
more likely to attack lemons that are bruised. It is thought that cover 
crops, especially vetch, which is also a host plant, favors this fungus. 
Bluestone will aid in its control, but it must be stronger than for brown 
rot. Professor Smith suggests that it may not be safe to use it strong 
enough to be effective on account of injury to the fruit, in which case 
the remedy must be to destroy it in the field. This fungus has been 
found recently attacking the orange roots of full grown lemon trees, 
entirely killing the trees in many instances, at the same time causing 
more or less gummosis. 
Gray Mold (Botrytis vulgaris). 
This is the dark colored decay of lemons in which a gray fungus 
develops. The fungus in the packing-house is not usually very serious, 
but as we have seen, it is a cause of gum disease. (See Monthly Bulle- 
tin, Vol. 2, No, 8, page 601, August, 1913.) 
Wither-tip (Colletotrichum gloeosporioides). 
This fungus kills the twigs at their ends, spots the fruit and leaves, 
and fells the latter to the ground. Mr. C. C. Teague says that this pest 
has cost the Limoneira lemon grove more than all injurious insects 
combined. I saw the plague in Mr. N. W. Blanchard’s orange orchard 
so bad that the foliage looked as if it had been blighted by fire. This 
disease is becoming more and more common in many orchards, and many 
are now fighting it with no little suecess. It seems to he erratic, depend- 
ing on seasons. Bordeaux mixture and lime-sulphur spray are the 
specifics to use in its control. Care must be taken in the use of the 
Bordeaux or injury may result. This is the more true if fumigation 
follows soon after the spraying. 
Damping Off (Rhizoctonia and Fusarium). 
Two fungi seem to be responsible for damping off. The first named 
fungus attacks the young seedlings at or just above the ground, causing 
