144 



THE CANADIAN HORTICULTURIST 



June, 1910 



Yellow Disease or Blight of Asters 



L. Caesar, Ontario Agricultural College, Guelph 



LAST fall, Mr. Wm. Hunt, florist at 

 the Ontario Agricultural College, 

 asked me to look into what ap- 

 reared to be a disease of asters that seem- 

 ed to be fairly prevalent last season in 

 many districts. After examining a num- 

 ber of plants at the college, I found that 

 the trouble is the same as was described 

 in Bulletin 79 of the Hatch Experiment 

 Station. Prof. R. E. Smith of that sta- 

 tion investigated this disease very care- 

 fully seven years ago and gave it the name 

 of the Yellow Disease or Blight of Asters. 



SYMPTOMS 



The symptoms are so conspicuous that 

 anyone can easily identify affected asters. 

 The diseased plants are characterized by 

 the leaves and upper parts of the stem be- 

 ing of a sickly greenish yellow color. 

 ^Vhen the flowers appear they too take 

 this greenish yellow color instead of be- 

 ing the normal white, red or blue, and so 

 on. Moreover, each flower assumes more 

 of a globular shape than is the case with 

 healthy flowers. This is caused chiefly 

 by the outer or ray florets curving in to- 

 wards the centre instead of expanding 

 somewhat horizontally. If the disc or 

 central florets are examined it will be seen 

 that they are more cylindrical and elong- 

 ated than is the case in healthy flowers, 

 and the stigma and style of the pistil pro- 

 trude about twice as far as they .should in 

 normal plants. The leaves in addition to 

 being sickly and yellowish, are usually 

 narrow and small, thus giving many of 

 the affected plants a spindly appearance. 

 Sometimes one or more branches will 

 show very little or almost no sign of the 

 disease, while all the other parts are af- 

 fected. Very badly diseased plants be- 

 come dwarfed and though many flowers 

 may appear they look like clusters of 

 very narrow greenish-yellow leaflets rath- 

 er than true flowers. 



CAUSE NOT KNOWN 



Professor Smith has given much study 

 to the cause of the disease and has not 

 found any organism present in any part, 

 .so that it is in no way associated with 

 root aphis, white grubs, fungi or bacteria. 

 Hence the true cause is still a mystery. 

 Practically all that has been discovered 

 along this line is that the plant for some 

 reason is unable to assimilate to the pro- 

 per extent the food that it manufactures 

 in its own green parts. Hence we have 

 an excess of starch and of certain acids 

 and of tannin pre.sent ; failure to use these, 

 of course, means semi-starvation. 



It is supposed by some that one flower 

 will contract the trouble from another, 

 or that it will be worse if plants are placed 

 in the same bed year after year, or grown 

 from seed from infected beds. Professor 

 Smith's experiments tend to show that the 

 disease is not contagious, and that it is 

 not spread by seed or by soil. He finds 



moreover that it cannot be due to lack of 

 certain substance.? in the soil because it is 

 about equally prevalent on different kinds 

 of soil, such as sand, sandy loam, clay 

 loam, and heavy clay. No variety .seems 

 to be exempt, though some years, as for 

 example last year at Ouelph, white asters 

 are worse attacked than others. This 

 does not .seem to hold in every case. It 

 has been found that the plants are not so 

 likely to be attacked if they are grown on 

 the raised benches of greenhouses or on 

 raised boxes outside. The cause of this 



is not known. From the fact that some 

 sea.sons the disease is much wor.se than 

 others, it is believed that weather condi- 

 tionstions must have a great deal to do 

 with its .severity. 



PREVENTIVK ilKASURE 



Though this disca.se, according to Pro- 

 fessor Smith, is not to any extent pre- 

 vented by .selecting new soil, yet there 

 are certain other diseases that attack 

 asters and as rot aphis are often severe, 

 it is wise to endeavor if possible to have 

 fresh soil, or .soil that has been sterilized, 

 in the hotbeds where the plants are start- 

 ed, and also to place the permanent beds 

 in fresh soil. 



Make a Fern Bed 



C. M. Bezzo, Berlin, Ontario 



A 



GROl'P of fine ferns makes a most 

 magnificent display and should be 

 found in every flower garden 

 where a suitable place can be found for 

 them. .Select a place in the shade of trees 

 or buildings. NIake the conditions as 

 rear as possible like tho.se under which 

 the fern lives and thrives in its native 

 haunts. The best ferns are not found in 

 dense shade where the tree tops form a 

 complete canopy impenetrable to the rays 

 of the sun, nor in the open where they 

 may be exposed. to the full blaze of the 

 noon-day heat. The ideal place for ferns 

 is vihere the tree tops are sufficiently 

 thick to merely break the direct rays of 

 the sun during the greater part of the 

 day. Where the shelter of trees cannot 

 be obtained, an east or northwest expos- 

 ure may be used. But in these locations 

 they should be protected by a fence or 

 some other arrangement, from the biting 

 north and east winds. 



The undergroimd conditions should be 

 studied the same as those overhead with 

 a view to imitating the native haunts of 

 the fern as much as possible. Our Cana- 

 dian woods are rich in ferns, and here is 

 the ideal place to study their require- 

 ments. The best are usually found in a 

 heavy leaf mould and wood-dirt. 



Go to your native woods for your ferns. 

 In this Canada of ours there is no neea to 

 buy from abroad ferns for the garden. 

 There is hardly a county in this province 

 of Ontario, and certainly not a province 

 in this Dominion, in the woods of which 

 ferns do not grow in plenty, which for 

 beauty of form and foliage, and ease of 

 culture, cannot be surpassed by those of 

 any other country in the world. 



In transplanting ferns they should be 

 lifted while the ground is wet, either early 

 in the .spring lx;fore the ground has dried 

 out, or immediately after a rain. Take 

 several pieces of burlap, one for each 

 fern, and large enough to cover the roots 

 and tie at the top to prevent the earth 

 falling away. Select the fern most pleas- 

 ing to your fancy and, after cutting the 



top off, if it has grown to any size, lift it 

 very carefully with a spade, leaving as 

 much of the soil as possible around the 

 roots. Wrap immediately in the burlap 

 to keeo earth and roots intact, and plant 

 in the fern bed as soon as possible, after 

 removing the burlap. Give a thorough 

 watering and put on a two-inch mulch of 

 pine needles, moss, sawdust or anything 

 ihrit will prevent the rapid evaporation of 

 the moisture. 



Early in the spring is the best time for 

 removing ferns, although it may be done 

 any time during the summer, but much 

 more care is required in order to be suc- 

 cessful. Where the moving is done in the 

 summer and the fern has made .some con- 

 siderable growth, the leaves and young 

 shoots should be cut back two or three 

 days in advance of the removal, in order 

 that the plant may regain in some meas- 

 ure its physical equilibrium before the 

 shock incident to its removal and the mu- 

 tiliation of its roots is imposed upon it. 



To prepare a bed for ferns the space 

 should be dug out to a depth of twelve to 

 fifteen inches and filled in with a compost, 

 made as follows: Two parts leaf-mould, 

 two parts meadow soil, or well rotted sod , 

 one part well rotted cow manure, and one 

 part sand. Add one pint of charcoal to 

 each bushel of the mixture as near as can 

 be estimated. There is very little danger 

 of adding too much. W'here the bed is 

 made .some little time in advance of the 

 nianting, one pound of wood ashes may 

 be added to each bushel of the mixture. 



."Xfter the plants are well started and in 

 active growth, they may be given liquid 

 food in considerable quantities — pulver- 

 ized cow or sheep manure one ounce to 

 two gallons ; or potash one ounce to five 

 gallons of water. 



Planting varieties not adapted to soil 

 and climatic conditions is one of the 

 worst errors in fruit growing. — Col. G. 

 B. Brackett, United States Pomologist, 

 before the American Pomological Socie- 

 ty at St. Catharines last September. 



