Selective Herbicides for Cultivation of Eucalyptus urograndis Clones

Table 2

Prevalence of bare ground 30, 60, and 90 days after treatment (DAT) for herbicides applied over newly planted Eucalyptus urograndis rooted cuttings either prior to weed emergence (PRE) or after weed emergence (POST). Treatments were evaluated at the end of the month indicated for each application timing and periodic assessment.

Treatment		Bare ground cover (%)^1
Herbicide	Rate (g ha^−1)	30 DAT	60 DAT	90 DAT^2
Applied PRE weed emergence^3
		May	June	July
Flumioxazin	290 ai	74 e	41 d	21 b–e
Flumioxazin	430 ai	80 de	48 cd	38 a
Imazamox	140 ae	74 e	38 d	21 b–e
Imazamox	280 ae	80 de	55 cd	29 a–c
Imazapic	140 ae	92 a–c	77 a–c	34 ab
Imazapic	210 ae	94 ab	84 a	37 a
Oxyfluorfen	1120 ai	57 f	13 e	14 de
Oxyfluorfen	2240 ai	89 a–d	45 d	14 de
Sulfometuron	26 ai	84 c–e	51 cd	17 c–e
Sulfometuron	53 ai	86 b–d	64 bc	26 a–d
Sulfometuron	105 ai	95 a	81 a	31 a–c
Nontreated control		33 g	19 e	13 e
Complete weed control		99	97	92
Applied POST weed emergence^3
		June	July	August
Flumioxazin	290 ai	25 f–i	30 bc	29
Flumioxazin	430 ai	27 f–h	31 bc	28
Imazamox^4	140 ae	40 de	34 bc	38
Imazamox^4	280 ae	57 a–c	44 ab	38
Imazapic^4	140 ae	53 b–d	43 ab	39
Imazapic^4	210 ae	70 a	54 a	42
Oxyfluorfen	1120 ai	17 hi	27 bc	23
Oxyfluorfen	2240 ai	22 g–i	27 bc	28
Sulfometuron	26 ai	43 c–e	28 bc	33
Sulfometuron	53 ai	36 ef	26 cd	28
Sulfometuron	105 ai	58 ab	38 a–c	34
Nontreated control		15 i	13 d	21
Complete weed control		98	92	95

LS-means within a column followed by the same letter for PRE or POST applications are not significantly different at using Fisher’s protected LSD. Means are for the two E. urograndis clones combined, since clone effects were not significant. LS-means for the complete weed control treatment were not included in LSD comparisons, because this treatment was applied repeatedly to provide as close to 100% bare ground as possible and was intended for comparisons of eucalyptus growth response to weed control.
²The effect of treatment was not significant for bare ground cover at 90 DAT for POST applications.
³PRE weed emergence treatments were applied April 29, 2009; POST weed emergence treatments were applied May 30, 2009. Seedlings were planted April 14, 2009.
⁴A nonionic surfactant was added at 0.25% (v/v) for POST applications of imazamox and imazapic as directed by herbicide labels.