Susceptibility of vining peas to injury by the pea midge, Contarinia pisi (Winn.), as related to temperature-dependent plant growth
1989
Joensson, B.G. | Nystroem, S. (Nordreco AB, Bjuv (Sweden))
The development stage, susceptible to injury by the pea midge, Contarinia pisi (Winn.), was defined by field trials and related to the temperature-dependent plant growth model in two vining pea cultivars of about the same earliness. One of these was a tripodded cultivar (with potential to set 3 pods/node) and the other was dipodded. The pea midge oviposited in the flower buds of 4-9.5 mm length in both cultivars. In the tripodded cultivar the first developed flower bud had reached the susceptible size 336 day-degrees (pea-D degrees, accumulated between 4.5 degrees C and 30 degrees C) after sowing. The corresponding value for the dipodded cultivar was 405 pea-D degrees. The last bud which could contribute to yield had passed the susceptible size 509 pea-D degrees and 579 pea-D degrees after sowing in the tri-and dipodded cultivar, respectively. The time interval when the yield-producing nodes were susceptible was identical for both cultivars. although 3 nodes contributed with harvestable pods in the tripodded cultivar compared to 4 nodes in the tripodded. As the pea midge requires a temperaturedependent time to develop from egg into fullfed larva, any eggs deposited on the plant close to harvest do not manage to develop into mature larvae. This sanitation effect was reached 535 pea-D degrees and 562 pea-D degrees after sowing in the tri- and dipodded cultivar, respectively. The time interval when oviposition led to mature larvae before harvest was longer in the tripodded than in the dipodded pea cultivar.
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