Early harvested almond orchards indicate a light crop in the Nonpareil variety, which means that our harvest season may be shorter than normal. Once the, harvest is complete, growers need to consider post-harvest cultural practices.
Post-harvest irrigations are a must for our almond orchards. Our soils don't store much water during the summer months due to harvest and high demand on evapotranspiration. The demand for water during the summer months is 17-acre inches. With this high demand of water, it's impossible to store any significant amount of water in the soil for use in autumn months. The evapotranspiration for the autumn months is about seven inches. This water is needed to keep the process of transpiration active in the tree. Transpiration is necessary for photosynthesis, a biochemical process that uses sunlight to convert atmospheric carbon dioxide into carbohydrates which will be used for bloom and fruit set in the 2001 crop.
Some of the orchards will run out of water during harvest and the trees will lose all their leaves. If you have this situation, you need to correct it since leaves are needed for the manufacture of carbohydrates. If you irrigate a defoliated orchard, you will get regrowth which will reduce bloom the following year. Nevertheless, you will still benefit by a post-harvest irrigation since it will prevent bud drop late in the winter. Post-harvest nitrogen fertilization is not recommended for orchards that have regrowth problems. Nitrogen will make the regrowth problem worse.
Post-harvest nitrogen fertilizer is a good idea in orchards that have kept most of their leaves. The nitrogen applied at this time will be absorbed by the roots. It then will be translocated to the top where it will maintain the leaves active and flower bud development. At leaf fall, this nitrogen will recycle back to the tree and will be stored for next year's bloom and fruit set. If you have maintained good yields with adequate nitrogen levels on the leaves, you need to apply 20 to 60 units of N with your post-harvest irrigations.
Winter pruning Pruning is an activity for the winter. However, Wilbur Reil, farm advisor in Yolo/Solano counties, demonstrated that pruning mature trees during October and November had no effect on yields, growth or nutritional levels when compared to the regular winter pruning. Therefore, pruning immediately after harvest should have no adverse effect on yields or nutrient levels the following year. Furthermore, fall pruning can give us the following advantages:
1. It will allow us to distinguish between dead or dying wood from productive wood.
2. It will allow us to expose lower fruiting wood to the sun in the fall.
3. It will eliminate the conflict between dormant spray and people pruning the orchard.
4. Fall pruning will allow the grower more time to prune his orchard.
5. It can provide work at a time when few other activities occur in almond orchards.
Irrigation, N fertilization and pruning are important post-harvest activities that may have a major impact on almond yields. Growers need to have their trees in good health in the fall. It is in the fall that trees will be manufacturing carbohydrates for next year's bloom and fruit set.