Plant Diseases of 1901 . 
5 
uncommon for such trees to die in the latter part of summer, when 
the fruit and foliage wither and cling to the dead branches. Such 
trees are usually comparatively loose in the soil, in fact, some of 
them may be tipped over while they are yet alive. Upon examina¬ 
tion the larger roots will be found to be in an advanced stage of 
decay, and the feeding roots finally become so reduced that there 
are not enough left to support the tree. 
Certain fungi are constantly associated with the diseased roots, 
and it is probable that they are ultimately responsible for the death 
of the tree. As a result of numerous examinations, it was found that 
these same fungi also attack the roots of trees that are apparently 
healthy. Now it is easy to conceive that these diseases may live on 
the roots of a tree for a number of years without doing much harm, 
but as soon as the tree is weakened from any cause the fungus makes 
rapid advance. 
Trees that take on yellow foliage from overirrigation suffer a 
temporary check in growth, from which they apparently recover in 
a short time. But if this is repeated year after year the ultimate 
effect must be very injurious. A wet, heavy soil, however, produces 
ideal conditions for the growth of root destroying fungi which appear 
to be abundant in our State, and when a favorable opportunity 
occurs they become destructive. 
Winter injuries, which result in sun scald, black heart, freezing 
of the roots and dry freezing of both roots and branches, are potent 
causes of the weakening of the vitality of trees in some sections of 
the State. Trees may be injured in some one of the above ways and 
yet not show any marked indication that anything is wrong. 
A good deal of damage is also done to fruit trees by the attacks 
of wooly aphis, which are abundant in many localities. They 
increase rapidly if left undisturbed, and the greater portion of the 
root system may soon be infested. These conditions result in serious 
injury and trees may even be ruined by such attacks. Root fungi 
are not slow to take advantage of the enfeebled roots, and it is likely 
that in many instances they rapidly extend these injuries. 
In some localities the natural drainage of the soil is poor, and 
it is evident that too much water is being used in irrigating. In a 
number of orchards visited the level of the water in the soil had 
been raised till the lower roots of the trees were apparently sur¬ 
rounded by a saturated soil most of the time. This is particularly true 
of small orchards, where the owners grow small fruits or truck crops 
between the rows to supplement the income from the orchard. Root 
fungi thrive remarkably well under these conditions, and the com¬ 
bination of causes is doing no small amount of damage. One orch¬ 
ard came under my observation where all of the trees on an area of 
about two acres had been ruined. (See Plate I.). Another orcli- 
ardist reports a yearly loss of about 25 out of an orchard of 1,000 
trees. Instances of this kind might easily be multiplied. 
