Vol. 16—1962 - NorthEastern Weed Science Society

.n_ots, "'hhin a few months after: ~pplication, mO$t:pt its effect is lost~.If
the aUll!DJeris moderately dry, treli\ted trees may n~:..defoliate completely that
season. In a wet summer, however, trees may defoliate at least twice.
A er;:'od of active 0 . and trans irat .·is necessar for effective
kill.' When enuron is app '. to the soi, tj,;lIIQyesinto the roots;
SOmewhataccording to the rapidi'l:r: pf grQwth. sucqessful usage has been~e
at Blackhawk from Me-rch through, No~mber, but mOliltJ:apid results were frqm
June thrOUgh Ausust.$ leaves ~OW, tlley transp1;;!li1 ~oving the chemical ,t-o
the leaves Where it affects Ptot9'~"f.;hesis. Photos;yl1thesis is naturally .pt
affected under the best growing conditions. Since tenuron seems to inhi¥;t
Ptotosynthesis directly, the lea'fes seem starved tor;' sugar, and chloroPtYJ1;l, .is
not manufactured. The lack of chl,Q~oPtyll further ;-educes the total Pt0i;pc
synthetic activity of the affected plants. Then t!¥!: plant appears to drapon
reserves of sugars and starches in the roots until these are depleted, and the
plant finally starves to death.
Applications in the late f.'Zldwet fall o.f ~60 did not show material
results until after the highly.act.ixe growth period ;t;n,midsummer 1961. ~ly
spring applications in 1961 did. not show any eftect,untll late in the s~r.
But applications Iilade between May2~ and July 5 .shQYe