Vol. 51—1997 - NorthEastern Weed Science Society

84
NEW TE
HNIQUE TO COMPARE EFFICACY OF MECHANICAL CULTIVATORS
D.L. Benoit', J. Recasens" and D. Cloutier'
ABSTRACT
We d communities vary floristically and quantitatively both between and within
experime tal sites rendering the comparison and interpretation of efficacy between
mechani I cultivators difficult. The objective of this study was to evaluate the
sensitivit of a new indicator species technique in estimating seedling control
following cultivation with different mechanical cultivators and to compare this
techniqu to the quadrat evaluation of in situ weed communities. The indicator
species t chnique used two species representing monocots and dicots (mustard and
ryegrass sown perpendicular to crop rows in plots where mechanical weeders were
to be te ted. This technique created known densities of indicator species at the
desired henological stage in all experimental plots. The weed community was
evaluate using six permanent quadrats of 25 cm by 1 m, three of which were placed
on the r and three in between the rows. The study was conducted on two sites,
one on 0 ganic soil and the other on a gravelly sandy loam. A split plot design with
four repli tions was used. The main plots were the mechanical cultivators and the
subplots were the evaluation methods. The cultivators compared were a
RABEW RKtine harrow, a BEZZERIDESspring hoe, a BUDDINGHwheel hoe,
a YETI RTM rotary hoe and a conventional rotary cultivator. Counts of weed
seedling and indicator species were collected before cultivation and five to seven
days aft r cultivation. The indicator species technique identified the wheel hoe as
the mos effective under hard crusted soil condition at reducing low ryegrass
populati n when seedlings were at the 2 leaf stage. All other cultivators failed to
achieve ignificant seedling reduction under those conditions. In dry organic soil,
the spri g hoe and rotary cultivator reduced significantly both high and low
populati ns of both monocots and dicots but with the spring hoe displacing a greater
number of seedlings. The tine harrow was not effective at reducing seedling
populati ns. In loose soil, no significant difference in seedling survival were noted
followin cultivation between the two techniques regardless of the mechanical
cultivato used. However under hard crusted soil, quadrats estimated a significantly
greater lant survival following cultivation than the indicator species technique. This
was attri uted to the more advanced growth stage of weeds. Quadrats allowed the
locatizat on of the area where the cultivator was effective at destroying seedlings ie:
on the r w or between the row, while the indicator species technique allowed for
effective unbiased comparison between mechanical cultivators with different mode of
action u der uniform and reproducible conditions and identified their individual faults
ie: stirn lation of a second germination or displacement and transplantation of
seedlin .
1 Weed ientist, Horticultural research and development centre, 430 Gouin blvd., Saint-Jeansur-Rich
lieu, Quebec Canada 13B 3E6
2 Prof, ept. Hortofructicultura, Botanioa i Jardinera, Universitat de Lleida, Lleida, Spain