F. Lopezgranados et L. Garciatorres, MODELING THE DEMOGRAPHY OF CRENATE BROOMRAPE (OROBANCHE CRENATA) AS AFFECTED BY BROAD BEAN (VICIA-FABA) CROPPING FREQUENCY AND PLANTING DATE, Weed science, 45(2), 1997, pp. 261-268
A mathematical model of crenate broomrape populations in broad bean as
affected by cropping frequency and planting dates in the absence of c
renate broomrape control practices was constructed using previously re
ported data. In consecutive broad bean cropping, broomrape populations
reached a maximum infection severity (D) of 62, 47, and 30 emerged br
oomrape m(-2) for early (mid-October), intermediate (mid-November), an
d late (mid-December) planting dates, respectively. The maximum D valu
es were reached earlier as planting dates were brought forward, taking
from 4 to 6 yr, starting from very low initial infections (D less tha
n or equal to 0.2 emerged broomrape m(-2)). If broad bean was cropped
every 3 yr, 15, 21, and 27 yr were needed, respectively, according to
the model, to reach the maximum D for the three planting dates conside
red. A sensitivity analysis was conducted to determine the effect of c
hanging the values of the main demographic parameters in broomrape lif
e cycle (germination, attachment, and seed loss) on the output of the
model under different management strategies (planting dates and croppi
ng frequency). Generally, an increase in seed attachment and a decreas
e in seed loss affected broomrape population dynamics. Between the TWO
processes evaluated, the time taken to reach the maximum infection se
verity (D) was less sensitive than the maximum broomrape population va
lues. Model predictions were validated using results from long-term fi
eld studies at the late planting date sown every year. Simulated value
s generated good predictions (R-2 = 0.82).