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NEW YORK, JULY 16, 1898 
i •J't'AV * 
BLACK-KNOT ON PLUMS. 
•WHAT VARIETIES MOST SUSCEPTIBLE ? 
What Can Be Done For It? 
One of our readers in Ohio has planted 112 plum 
trees on a village lot. They have been well cared for, 
and now promise to yield considerable returns. The 
income from this number of trees at their best will be 
several hundred dollars, as judged by the few trees 
that have begun bearing. A danger now appears in 
the form of black-knot. The Lombards and Guii show 
the worst of the black-knot, these varieties being the 
most profitable trees in the collection. Richland, 
Bradshaw, Grand Duke, Shipper’s Pride and Peter’s 
Yellow Gage have never had a single knot. The owner 
says that he trimmed off the knots on the trees early 
in May when they first began to 
swell, and applied iodine. In a few 
days, nearly all the foliage turned 
black and dropped off. The knot, 
however, seems to be thoroughly 
killed, and the wound is healing. 
This matter of black-knot means a 
good deal to a man in this situation, 
lie has finally succeeded in getting 
the village council to rule that, as 
soon as foliage drops, every tree in 
the village badly infested with 
black-knot must be cut down and 
burned. This is a good rule to make. 
Our friend says that the disease in 
his trees came from a few old Dam¬ 
son trees owned by a neighbor 
“ which had not borne plums enough 
in 10 years to make a good pie ”. 
There is no sense in letting such old 
trees stand to infect a good orchard. 
This orchard means a good deal to 
our friend, and the answers to the 
following questions will help plum 
growers : 
THE QUESTIONS. 
1. Have any of ttie readers of The R. N.-Y. 
been bothered with the black-knot this year 
worse than last, and is it because of the 
mild Winter ? 
2. In paring off the knots from limbs, 
what is the best thing to coat the wound to 
kill the roots of the knots, and act as a 
healing application to the wound ? 
3. Is black-knot worse some years than 
others, and would you expect good results 
from spraying with Bordeaux Mixture as a 
preventive ? 
4. What time of the year, and how many 
times, would you spray as a preventive of 
the knot ? 
5. What European varieties, with you, 
have been the most subject to knot ? 
6. What varieties have been least subject 
to knot ? 
7. How badly must a tree be infested with 
knot to be incurable ? 
Don’t Let Trees Overbear. 
1. I have grown plums and cher¬ 
ries for years, and have never had any serious trouble 
with black-knot. It is very likely this trouble will 
be more common this season than last, owing to the 
large crop of fruit last season. In this section, there 
was the largest crop of plums ever known, and grow¬ 
ers have not yet come to a realizing sense of the neces¬ 
sity of thinning the fruit. The plum trees were so 
weakened by overbearing that they became an easy 
prey to the black-knot, and all other diseases of the 
plum. 
2. I have found turpentine or kerosene the best 
things to coat the wounds. / lways take off the entire 
limbs if not too large, and burn them. 
3 and 4. Black-knot is always more prevalent in 
years following a heavy crop of fruit. I do not be¬ 
lieve that spraying with anything will Jprevent this 
troublesome disease. Keep the trees in a healthy, 
growing condition, and never allow them to overbear ; 
this will do more good than spraying. 
5 and 6. On my 200 plum and over 300 cherry trees, 
I do not find, from year to year, three pieces of black- 
knot ; therefore, I cannot say that any one variety is 
more subject to it than another. 
7. If I had a tree that persisted in bringing forth a 
crop of black-knot, I would certainly remove it, root 
and branch. The secret of success in growing fine 
plums, lies in keeping the trees in a thrifty, growing 
condition, and never letting them overbear. Never 
prop up the branches of a tree, but thin the fruit until 
the tree can bear up its burden ; by following this 
plan, there will be no off years of fruiting, no black- 
knot, no small, inferior fruit, and no glut in the fruit 
market. No. 1 fruit always sells at good prices. My 
neighbors’ unthinned plum trees of last season, are 
now dead, or feebly struggling for existence, while 
my own trees that were heavily loaded, but properly 
thinned, are again carrying a tremendous load of fruit 
from which I am taking from one-half to two-thirds 
of the entire crop, and my trees have already made 2% 
feet or more of new wood. a. a. halladav. 
Vermont. 
Paint Wounds With Bordeaux Mixture. 
1. Blaek-knot is not spreading in eastern New York, 
or developing as much as it did five years ago, because 
most of the old plum trees have died, and but few 
have been set again. 2. Paint the wounds with Bor¬ 
deaux Mixture. Kerosene oil is good, but many injure 
their trees by putting it on too freely. 3. Yes, there 
seem to be periods when conditions are favorable for 
a general development of the fungus, and the plum 
f 
] 
1 
would spray from March to August, twice a month. 
5. Reine Claude, Hudson River Purple Egg, Brad¬ 
shaw, and the Damsons, have been very susceptible to 
the attacks. 6. Quackenbos and the prunes have 
been free more largely than other kinds. If all who 
plant plum trees, would be vigilant in keeping their 
trees clean, there would be little difficulty in any 
locality, even in years when the 
conditions are right for the fungus 
development. geo. t. powell. 
Columbia County, N. Y. 
Cut Back According to Variety. 
1. Have seen very little new growth 
of the black-knot this season, in this 
section. We get more in a hot, wet 
season like last, or at least, it was 
more prevalent last year than this. 
2. I use tincture of iodine to paint 
over the knots when they are small; 
the large ones I cut out all I can, 
and then apply the iodine. One 
coating does the business for me, 
and then I cover with melted graft¬ 
ing wax, or equal parts resin and 
tallow melted, which makes a better 
coating. 3. Black-knots are worse 
some years than others. As to the 
Bordeaux Mixture being a preven¬ 
tive, I can’t say, as I never used it. 
4. Were I to use the Mixture, I 
would apply early, before the leaves 
start, at least two applications, and 
two more after the fruit had set. 
5 and 6. Of all varieties, the Lom¬ 
bards are the worst to knot with us. 
The newer varieties that have been 
set in this section thus far, seem to 
be proof against the knot. 7. That 
depends on the varieties, I think ; 
some will bear more cutting back 
than others. I have old stubs of 
Lombard with two-thirds of the old 
top gone, that are loaded with fruit 
at present, while the Reine Claude 
seems to die, to spite me for cutting 
them back, rather than from the 
effects of black-knot. Black-knot 
made a clean sweep through this 
section about five or six years ago, 
taking cherries as well as plums, 
and in coasequence, the area of plum 
growing is not what it was once with us. 
Vermont. w. n. holmes. 
Black-knot May Be a Blessing. 
1. Black-knot on plums has been no worse here this 
year than in others, in fact, not so bad. 
2. The best application 1 have ever tried is a mix¬ 
ture of turpentine, linseed oil and rossie paint, which 
is simply ground iron ore. The object of the linseed 
oil and pigment is to coat the wound, while the tur¬ 
pentine kills the spores of the black-knot. Clear tur¬ 
pentine will kill all the spores, but it will, also, kill 
the healthy growth so far as it reaches, and if put on 
clear, it is very difficult to prevent its running on 
more of the tree than is desired. By putting oil with 
it, and mixing in the paint, it may be made so thick 
SINGLE CLUSTER OF SAMPLE STRAWBERRIES. Fig. 221. See Rukalisms, Page 498. 
