Selective Herbicides for Cultivation of Eucalyptus urograndis Clones

Table 5

Percentage of Eucalyptus urograndis trees with no or minor injury symptoms at 30, 60, and 90 days after treatment (DAT) for herbicides applied over newly planted 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		Percentage of trees with no or minor injury symptoms
Herbicide	Rate (g ha^−1)	30 DAT	60 DAT	90 DAT
Applied PRE weed emergence^3
		May	June	July
Flumioxazin	290 ai	100 a	100 a	95 a–c
Flumioxazin	430 ai	100 a	100 a	88 bc
Imazamox	140 ae	97 a	100 a	78 c
Imazamox	280 ae	99 a	100 a	92 a–c
Imazapic	140 ae	0 c	0 b	0 d
Imazapic	210 ae	0 c	0 b	1 d
Oxyfluorfen	1120 ai	100 a	99 a	82 bc
Oxyfluorfen	2240 ai	100 a	99 a	93 a–c
Sulfometuron	26 ai	99 a	99 a	81 bc
Sulfometuron	53 ai	96 a	100 a	99 ab
Sulfometuron	105 ai	53 b	99 a	100 a
Nontreated control		100 a	100 a	96 a–c
Complete weed control		99 a	100 a	99 ab
Applied POST weed emergence^3
		June	July	August
Flumioxazin	290 ai	99 a	99 ab	99 a
Flumioxazin	430 ai	99 a	100 a	100 a
Imazamox^4	140 ae	6 cd	100 a	100 a
Imazamox^4	280 ae	0 d	100 a	100 a
Imazapic^4	140 ae	0 d	0 d	73 b
Imazapic^4	210 ae	0 d	27 c	56 b
Oxyfluorfen	1120 ai	100 a	100 a	100 a
Oxyfluorfen	2240 ai	99 a	100 a	100 a
Sulfometuron	26 ai	29 b	98 ab	100 a
Sulfometuron	53 ai	10 bc	99 ab	97 a
Sulfometuron	105 ai	8 c	86 b	100 a
Nontreated control		100 a	100 a	100 a
Complete weed control		100 a	100 a	100 a

Slight foliar chlorosis, slight foliar necrosis, and slight defoliation (slight = symptom severity index 1 in a 0–4 scale) were considered minor injury symptoms, whereas any observed fasciculation, lateral shoot dieback, or leader dieback were not regarded as minor.
²LS-means within a column followed by the same letter for PRE or POST applications are not significantly different using Fisher’s protected LSD at . Means are for the two E. urograndis clones combined since clone effects were not significant.
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 at 0.25% (v/v) was added for POST applications of imazapic and imazamox as directed by the herbicide label.