CHE REFERENCE LIBRARY - ZetaTalk

CERTAIN ELEMENTS IN NURSERY PRACTICE 197Pen frol. -- Spraying with lime-sulfur solution I to 40, ordusting with 90 parts dry sulfur plus 10 parts powdered arsenateof lead, proves etiective in the control of apple- and pear-scab.For nursery stock, the first treatment should be made soonafter the first new Icaves appear. This application should befollowed 1-q. at least three more treatments at intervals of twot,o three Fveeks.ilS a, general recommendation for nurseries, it is not consiclerednecessary to treat varieties of pear trees for scab exceptthe I”letnish. In most nurseries it is not necessary to treatapplt~s each yc~ for sca.b, but in some cases the treatmentpro\‘cs profitahlC Where t.hc: disease is commonly observedon c(r’rtain \Gt+t~s of apples, such as McIntosh and TranscendctltNY&~, spra.ying or dusting is advisa,ble.:\PPIX I’( ~WDISI~Y-MILDEW. ---.- This disease is most commonlyohserved in the nursery on the foliage and young shoots of theapple seedling stoc*k. When it appears early in the summer,the growth of the seedlings is checked and the bark does notpeel readily at budding time.Ikscriptin~~. - ‘I’llt~ disease appears as grayish white, feltlikeareas on the foliage, varying in size from a minute speckto an inch in diatnctt-ar. The diseased leaves are stunted andhaye a tcndcnq, t.o crinkle and curl up. Aft’ected shoots arestunted ;tticl appear tnuch shorter than healthy twigs.(‘n Ilsr’. -- The disease is caused by a fungus, .Z%~!osph~~alwcotricho. The grayish patches of mildew on the leaf or theshoot. consist of a tangle of fine threads or strands of thefungus. Tl lis . 1 oosely interwoven mass of threads (known asm~*celium) produces spores that, are carried by wind and rainto other lea,ves where they produce new patches of mildew.The fungus lives over winter between the dormant bud-scalesor by means of special fruiting bodies.C~olltrol. -- Lime-sulfur solution 1 to 40 is eflective to a