Page 48 - Volume 6, Issue 1, January 2013

© Benaki Phytopathological Institute
Travlos et al. 46
in digestibility and protein content of the
alfalfa hay (Cords 1973). Usually, alfalfa and
weeds are harvested together and thus the
quality of the hay is significantly degraded.
This degradation is even higher, especially
in the case of weeds such as silverleaf night-
shade that animals are reluctant to graze be-
cause of the spiny leaves and stems (David et
al., 1945). For the effective control of silver-
leaf nightshade, several mechanical (David
et al., 1945), biological (Keeling and Aber-
nathy, 1980; Parker, 1986), or chemical meth-
ods (Philips and Merkle, 1980; Eleftherohori-
nos et al., 1993; Westerman andMurray, 1994)
have been proposed. However, an integrat-
ed weed management approach based on a
rotation regime with competitive alfalfa cul-
tivars is rather required for an effective con-
trol of noxious species, such as silver night-
shade.
Another critical thing to be taken into ac-
count is that for a perennial crop like alfal-
fa, high weed populations in the first year
may adversely affect crop yield and quali-
ty in subsequent years (Smith et al., 1990). It
is well documented that controlling weeds
during the establishment year reduces stress
on alfalfa and ultimately increases yield in
the following years (Stout et al ., 1992; Trav-
los, 2011). Consequently, the careful selec-
tion of the most productive and weed com-
petitive alfalfa cultivars could be of great
importance during the crucial year of crop
establishment.
Conclusions
Our results showed that the weed compet-
itive ability and forage yield of alfalfa cul-
tivars might have a substantial range and
should be certainly taken into account. An-
nual forage yield loss in the case of less
weed competitive alfalfa cultivars was high
and up to 26%, while after the selection of
the most productive and competitive cul-
tivar (i.e. Hyliki) the reduction was signifi-
cantly lower and forage yield could be up to
28% higher, even with the presence of the
noxious silverleaf nightshade. Similar stud-
ies should be continued including differ-
ent alfalfa cultivars, soil and climatic condi-
Figure 1. Relationship between forage yield of alfalfa and biomass of Solanum elaeagnifolium for three alfalfa cultivars
(Gea, Dimitra, Hyliki) and four harvests during the first year of crop establishment.