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OCTOBEB 21, 1920 



The Florists^ Review 



27 



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DISEASES OF SWEET PEAS 



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OST serious of the pests 

 with which the sweet pea 

 has to contend is the green 

 fly. We find it is respons- 

 ible for what is commonly 

 known as "streak dis- 

 ease," an irregular strip- 

 ing or mottling of leaf and 

 flower. It is only while the 

 plants are small that the 

 Hy is able to infect them. From the 

 time the plants are up until well into 

 September they should be sprayed twice 

 a week with a strong solution of nico- 

 tine. We use a half -pint of nicotine to 

 six gallons of water, put on under strong 

 pressure. If the plants are not exces- 

 sively dry, this proportion will not harm 

 them. As the weather becomes cooler, 

 once a week will do, and throughout the 

 winter months we paint undiluted nico- 

 tine on steam pipes every month or six 

 ■neeks. 



All openings near the ground, such as 

 doors, should be kept carefully closed 

 to guard against the entrance of green 

 fly from outdoors. According to our 

 observation, plants exposed to such 

 openings are seldom free from the streak 

 disease. The pests seem to keep too 

 close to the ground to find their way 

 through a side ventilator. 



Every Plant Infected. 



Several seasons ago we planted a 

 newly built house with early peas and 

 postponed the glazing until late Sep- 

 tember, hoping in this way to take ad- 

 vantage of more natural conditions for 

 starting the plants. By November we 

 ilecided that not a plant in the house 

 had escaped the streak disease. Scien- 

 tific investigators diagnosed the trouble 

 as a form of root-rot with which the 

 plants could be infected through aphis. 

 They stated that the germ of this trou- 

 ble was lodged in the soil and advised 

 thorough sterilization with steam or for- 

 maldehyde. We used both disinfectants, 

 leaving out one bed as a check on the 

 others. The next crop of plants in all 

 these beds came equally well. While 

 this does not definitely prove anything, 

 we have had no streak trouble since 

 then, realizing that green fly must be 

 kept down at any cost. 



Plants affected with the streak dis- 

 ease gradually weaken and die. The 

 irregular markings on the flowers make 

 them unsalable. While affected plants 

 do not spread the disease, they should 

 be removed to give room for fuller de- 

 velopment of the remaining plants. Un- 

 "ler liberal conditions a sweet pea plant 

 is capable of large development. If the 

 disease removes plants to the extent of 

 leaving them eight to ten inches apart, 

 the row will be well filled out; if no 

 plants are lost, they do not have room 

 to branch so freely and the final results 

 are about the same. 



Supporting tlie Vines. 



We pay no attention to the first 

 growth, but leave it on the ground to 

 encourage the breaking of the lower 

 eyes, which make the future plant. 

 After the lower breaks are well along, 



This Is a continuation of the article on the 

 culture' of sweet peas by George J. Ball, of Glen 

 Bllyn, 111., In the October 7 Issue of The Review. 

 In a later issue he will write concerning the 

 proper methods of marketing these flowers. 



the original growth can be cut away 

 to advantage; to tie it up only adds 

 to the density of the lower growth, 

 where rot sometimes sets in. If the 

 bed is not well exposed or the root action 

 is arrested, these lower breaks do not 

 occur, but the original growth develops 

 into the plant. 



The upright strings should be close 

 enough to allow each growth to be cared 

 for individually. Do not bunch or tie 

 a number of them together. For tying 

 we use a light-weight 3-ply cotton twine. 

 Early plantings, under favorable condi- 

 tions, will reach a height of fifteen 

 feet. Such a growth must be substan- 

 tially supported. We find it necessary to 

 divide the support for this growth into 

 two sections. The overhead wire for 

 the first section, being about halfway 

 up, forms the lower wire for the upper 

 section. If string is run up twelve to 

 fifteen feet it will sag, leaving the 

 lower part of the vines in contact with 

 the ground, which will rot them. The 

 purlin supports of our houses are con- 

 nected with a 1^-inch pipe by means 

 of split tees. These cross-pipes are 

 about eight feet from the ground and 

 are used to support the first overhead 



wire. Across these pipes we lay 10-inch 

 planks, from which all work is done in 

 the upper growth. 



Regulating the Temperature. 



Mildew should be carefully guarded 

 against during October. Too much air 

 or a sudden drop in temperature, with 

 a damp atmosphere and no heat, will 

 spread this trouble fast. If the plants 

 are gradually hardened and accustomed 

 to the change, there will be little trouble. 

 For winter-blooming stock we like to 

 keep the temperature down to 45 de- 

 grees; this produces the kind of stock 

 that responds to a temperature of 50 

 degrees, beginning November 1. The 

 originator of these winter-blooming 

 Spencers recommends a night tempera- 

 ture of 55 degrees. Tljey open well at 

 this temperature, but if good stems, 

 with flowers that will stand long-dis- 

 tance shipping, are wanted, we find they 

 should be held down to 50 degrees. If 

 grown cooler, the wings develop an 

 objectionable green edge, Eaising the 

 temperature to 55 degrees to increase 

 the pick for a special occasion will do 

 no noticeable harm, though the stems 

 shorten and the life of the plant is cut 

 short in direct ratio to the amount of 

 heat applied. 



Bud-Dropping. 



The most serious obstacle to the suc- 



Sweet Peas of Sturdy Growth at Greenhouses of Geo. J. Ball, Glen Ellyn, HI. 



