Vol. 51—1997 - NorthEastern Weed Science Society

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Table 3. Stand density of oats after weed control treatmentsin 1992, 1994and 1995.
----I--------:-~--~~--~--
Rotary hoe
Tine weeder
2,4-D
Untreated check
1992 1994 1995
---------------- 1,000,OOO's I ha ----------------
1.53 1.81 2.00
1.42 2.46 2.31
1.89 2.06 2.19
2.02 2.61 2.33
Untreated v, othersl * * N.S.
Mechanical v, 2,4-b * N.S. N.S.
Ro hoe v, tine i eeder N.S. * N.S.
Statistical signific ce of orthogonalplanned comparisons:* P < 0.05; N.S. P > 0.1
Oat yields did notdiffer among treatmentsin any year. Mean yields were 3,500, 3,800 and
3,500 kg/ha in 199~, 1994 and 1995,respectively. Apparently,the crop was sufficiently
competitive to withstand even the moderately severe infestation of 1992,and sufficientlyplastic
to compensate for density reductions due to cultivation. In a Nebraska trial (7) oat yields were
improved by herbicdes in only one year out of three. Other studies have similarly shown a lack
of response or eve~ a negative response of small grain yield to weed harrowing (9, 12, 13). This
is probably relatedltothe inverse relation between weed control and crop survival noted above.
An integrated approachin which planting density is increased when using cultivation might help
the crop quickly aqhieve a full canopy despite damage. That in tum could allow some additional
yield through either additional capture of resources or competitivesuppression of the weeds (5).
However, unless tliefield is quite weedy, the yield incrementmay be too small to pay for either
mechanical or chef.ical control measures. In the NortheasternU. S., where small grains
constitute a relatively small proportion of the crop mix, a better strategy may be to concentrate
weed control measureson the preceding row crop, plant into a relatively clean field, and forgo
chemical and mechanicalmeasures on the small grain crop.
ACKNOWLEDGEMENTS
We thank D. Tiffany and J. Conklin for performingfield operations, and A. Farsrad, M.
Paeenza, C. ASarOtS. Boerke, L. Mohler, L. Solomon,A. Galf~rd, G. Nesselage, K. Jabbs, L.
Alexander, J. Ottk~, H. LeBarre, S. Cady, R. D. Perrotte, M. Feingold, and S.-S. Chen for help
with data collectiop. This work was supportedin part by funds from the SustainableAgriculture
Research and EdueationProgram, Northeast Region (CooperativeAgreement 92 COOP-I-7191),
and by Hatch funds (RegionalProject NE-92, NY(C)-183458)from the Cornell Agricultural
Experiment Stati0f'
1.
LITERATURECITED
Bridges, D.~. 1992. Crop losses due to weeds in Canada and theUnited States. Weed
Science Sliety of America, Champaign,IL.
2.
Colquhoun.Il.B. and R.R. Bellinder. 1994. Innovativemechanicalweed control systems
for snap berS' sweet com, and transplantedbroccoli. Proc. N. E. Weed Sci. Soc. 48:102.