Assessing a posible spry intercept or evaluating if a preventative spray done several days ago on its activity against a later downy mildew infection has to take in consideration how much unprotected leafs or cluster surface has been formed meanwhile. FieldClimate offers a simple growth model assessing the formation on new leafs per shoots and the proportional formation of cluster surface on base of temperature and day length.
In the temperature range from 10 to 24°C plant growth is assumed to be proportional to temperature. Temperatures higher than 24°C will not been assumed to be more favourable for plant growth then 24°C. During the night it assumes a resporation rate proportional to temperature again. Whereas this rate is assumed to be highest at 34°C and to be in maximum 25% of the highest posssible daily assimilation rate.
Shoot groth of in this model will vary in between 0 and 7 leafs per week before reaching its maximum. After bloom an increasing part of growth is coming form the clusters and berreis and the shoot groth is reduced by this. Before veraison it is assumed that less than 40% or the assimilates will be available for shoot growth.