Post Written by: Amanda Green, Tree Fruit Specialist, OMAFRA
Leaf Tissue Sampling Time for Nutrient Analysis
Terminal Buds are setting across the province and this is the best time to collect tissue samples for plant nutrient analysis. Nutrient concentration in the leaves is not stable throughout the season as nutrient supply and internal nutrient cycling alters the nutrient profile of the leaf as the shoots and leaves grow. (Neilsen and Neilson, 2003). When terminal bud set, this year’s shoots stop growing and nutrients in the leaves have not yet started to be exported to the shoots, this is when nutrients are most stable (Hoying et al., 2004).
- Sample 10 leaves from 10 representative trees
- It is best to sample from the same trees each year.
- Sample trees from different blocks separately, the same way that you would sample your soil or manage your fertilizer separately, block by block.
- Avoid collecting damaged or abnormal leaves.
- Collect tissue samples into labelled paper bags and deliver right away.
- If you can’t deliver right away, dry the leaves in the sun or in an oven at 65°C or less.
- Remember, plant tissue sampling does not replace soil testing, the results are the most useful with a visual assessment of the crop and current soil conditions and a recent soil test
For foliar nutrient sufficiency ranges for apples see Table 18 in the OMAFRA Soil Management, Fertilizer Use, Crop Nutrition, and Cover Crops for Fruit Production webpage.
If you haven’t already applied calcium sprays, they should be applied now to apple cultivars that are prone to bitter pit, like Honeycrisp, Cortland, Empire and Northern Spy. Apply calcium at two week intervals at least four times. Calcium is a nutrient that moves with the xylem which transports water to fully developed leaves. It is not mobile in the phloem, which is responsible for transporting sugars from photosynthesis to new growth and fruit. Because xylem transport to the fruit is limited there is difficulty transporting sufficient calcium to the fruit. Most calcium flows into the fruit 4-6 weeks after bloom and starts to decline after that. For more information on calcium application see the OMAFRA Soil Management, Fertilizer Use, Crop Nutrition, and Cover Crops for Fruit Production webpage. For more information on how to manage bitter pit see Bitter Pit Control in Apples Factsheet.
It is getting quite dry in many apple growing areas of the province. According to the Agriculture Agri-Food Canada Agroclimate maps, areas east of Prince Edward County have had less than 40% of normal precipitation over the last 30 days and 40-85% of normal precipitation over the last 60 days. Toronto to Kingston, Grey County and Niagara Region have received 60-85% of normal precipitation over the last 30 days and 40-85% of normal precipitation over the last 60 days. In Southwestern Ontario, south of Guelph and Toronto, precipitation over the last 30 days have been close to average or higher but these 30 day precipitation numbers include the heavy rains in late June. Probably a substantial amount of this rain did run off the soil since it came down fairly heavy. From what sources in different regions have told me and what I have seen around Norfolk County and Niagara Region, Southwestern Ontario is due for rain as well. The precipitation over the last 60 days in most of the Southwestern Ontario has been 60-85% of normal.
In the last apple update blog post in June, I provided some links on irrigation scheduling, here they are again: OMAFRA Irrigation Page and two blog posts wrote by Rebecca Shortt, Engineer, Water Quantity, OMAFRA, during the dry year of 2016 Irrigation Update and How Long do I Run my Drip Lines . Also, soil moisture monitoring is a great tool to manage soil moisture and irrigate with more precision see Monitoring Soil Moisture to Improve Irrigation Decisions Factsheet.
Hoying, S., M. Fargione and K. Iungerman, 2004. Diagnosing Apple Tree Nutritional Status: Leaf Analysis Interpretation and Deficiency Symptoms. New York Fruit Quarterly 12: 16-19
Neilsen, G. H. and D. Neilsen, 2003. Nutritional Requirements of Apple. p. 267-302. In: D. C. Feree and I. J. Warrington (eds.) Apples: Botany, Production and Uses. CAB International