THE NATIONAL NURSERYMAN 
315 
NURSERYMEN’S PROBLEMS IN FUNGOUS AND 
BACTERIAL DISEASES 
Paper Read by Prof. H. S. JACKSON, Plant Pathologist, Oregon Agricultural College and Experiment 
Station, at the Portland Convention 
It is not my purpose today to discuss at any length the 
various diseases which affect nursery ^ stock, but rather to 
outline as briefly as possible some of the general problems 
which confront nurserymen in connection with losses caused 
by fungous and bacterial diseases or with the dissemination 
of these diseases through nursery stock. My observations 
have been that in general nurserymen are more up-to-date 
in regard to the control of insect pests than of fungous and 
bacterial diseases. This is probably due to a better under¬ 
standing of insect troubles in general on the part of nursery¬ 
men, and I believe that it is also largely due to the fact that 
with few exceptions there is a more rigid inspection for 
insect troubles than for fungous diseases. 
It is a fact, however, that there are certain very serious 
troubles of nursery stock some of which like the crown gall 
and hairy root cause a great deal of loss to the nurseryman, 
and others which perhaps cause min6r losses but are im¬ 
portant because of the possibility of their being commonly 
distributed through nursery stock and thus disseminated 
widely throughout orchard sections. 
There are two reasons why nmserymen should be inter¬ 
ested in these troubles. Probably the primary one from 
the nurseryman’s standpoint would be because these troubles 
cause financial loss to himself. There is, however, another 
reason fully as important. The nurser3rman should be 
thoroughly familiar with the various troubles and should 
make every possible effort to control them in order that he 
may establish and maintain a reputation among growers 
for sending out stock free from disease. There is a great 
deal of complaint among growers that certain diseases are 
introduced into their orchards through nursery stock. 
This is especially true when any trouble appears in a young 
orchard. It is undoubtedly true that most of such accusa¬ 
tions are unfoimded. It is also certain that in many cases 
certain serious diseases are disseminated through nursery 
stock. This may be entirely unintentional on the part of 
the mu:ser3nnan. He may not even be aware that the partic¬ 
ular disease in question exists in this stock. In fact there 
is altogether too little known by anyone, not only by the 
nurseryman, but on the part of experts in plant diseases 
as well, in regard to the diseases that are disseminated in 
nursery stock and just how general these troubles are. 
For example in the Northwest complaint is often made 
that apple tree anthracnose is disseminated in nursery 
stock. It is entirely possible for this disease to be dis¬ 
seminated in this way and undoubtedly some cases do occur, 
but I do not think that any one is in a position to say just 
how much or how little dissemination occurs. 
There is another trouble which is very common in the 
orchards of the Northwest and which seems to be becoming 
more common, known as the “mushroom root rot.’’ We 
know nothing at the present time regarding the dissemina¬ 
tion of this trouble through nursery stock though it is pos¬ 
sible that it might be disseminated in this way. 
I mention these points not with the idea of criticising 
nurserymen, but rather to point out the fact that there arc 
certain important problems here which need investigation 
and which should be of vital interest to the nurserymen. 
Inspection of nursery stock is becoming more general and 
more rigid each year. Often shipments have been con¬ 
demned on suspicion, in many cases without sufficient 
scientific information to justify such a decision. Would it 
not be better if investigations could be made before the 
nurserymen are forced to enquire into the facts after having 
their stock condemned? 
Plant Pathologists all over the country are making 
investigations regarding plant diseases in general. Their 
work, however, necessarily deals primarily with the prob¬ 
lems of the growers. Very little attention has been paid 
by them to the problems which are purely the problems of 
the nurserymen. It is only where the interests of nursery¬ 
men and the grower overlap that extensive investigations 
have been made, consequently it is probable that there may 
be important diseases especially here in the Northwest, 
which may be causing considerable loss to the nursery 
industry. An investigation of these general troubles by 
an expert plant pathologist might reveal many ways in which 
losses to the nurserymen could be reduced and would cer¬ 
tainly result, in many cases, in the production of cleaner and 
better nursery stock. 
There is a tendency among many nurserymen to believe 
that fumigation is a cure all, and, tha^ after complying \vith 
the requirements for fumigation the stock should be clean 
of all insect pests and plant diseases. 
I wish to call your attention to the fact that fumigation 
is useless as a control measure for many fungous diseases, 
especially any which are carried over the dormant season 
in the tissues of the plant. Many such troubles may be 
controlled, however, by careful spraying in the nursery. 
To give a specific instance, a disease known as California 
peach blight which is very prevalent in certain sections of 
the Northwest is undoubtedly widely distributed through 
nursery stock. This disease appears as small puqjlish 
spots on the twigs or small cankers around the buds. The 
fungus would be carried over winter in the tissues of the 
bark. No method of fumigation would kill the fungus in 
that condition. The disease, however, may be readily 
controlled by proper protective spraying methods which 
would prevent the disease from obtaining an entrance to the 
tissues. 
Probably the disease which has received more attention 
than any other both by the nurser^nnen and fruit inspectors 
