Optimising Horticultural Crop Yields: The Importance of Leaf Testing

Leaf testing during key growth stages throughout the summer is a useful tool for optimising the yield and quality of horticultural crops. With increasing variability in weather patterns due to climate change, maintaining optimal plant nutrition is one activity that can help reduce uncertainty when growing high-value crops.

Accurate sampling is crucial, and detailed instructions can be found in our Crop Guides 

Kiwifruit Update 

Hill Labs offers interpretive ranges for most common horticultural crops in New Zealand, including tentative "medium ranges" for newer kiwifruit varieties. We are currently reviewing and refining kiwifruit leaf ranges for various cultivars and growth stages.  

We have recently updated our kiwifruit naming convention for clarity. On sample submission app and reports you will now see Kiwifruit “G3” sample types have been renamed to Kiwifruit Gold3, Kiwifruit “G14” to Green14 and Kiwifruit “Red” to Red19. 

Key Sampling Guidelines 

When submitting leaf or petiole samples, clearly indicate the crop variety on the request form. This ensures that the appropriate interpretive ranges are applied to your samples. 

If any spray residue is visible on the leaf tissue, an acid-detergent wash can be requested. Keep in mind that some spray residues adhere strongly, and this wash may not completely eliminate trace element contamination. 

Combined Leaf & Petiole Testing for Grapes & Potatoes 

Users of our seasonal Combined Leaf and Petiole test profiles for grape and potato samples are reminded to get in touch to order small ziplock bags for petiole sample collection. These bags are not available through our online platform, so please get in touch directly. 

Before sampling, label both the larger plant bag and smaller petiole bag. At sampling, place the petiole fraction inside the smaller ziplock bag and then into the larger bag with the leaf blade sample. You can then scan the sample bag’s barcode using the submission app. If you’re not using the app, submit samples using the usual request form, noting that a grape tissue-specific form is available online. 

Nutrient Analysis 

The Combined Leaf and Petiole profiles (CGP, CPotP) enable analysis of mobile nutrients (NO3-N, P, K, Mg) in the petiole's conductive tissue, as well as the full range of the nutrient sink in the leaf blade. For more details, consult the Grape or Potato Crop Guides in the client resources section of our website. 

Sample Integrity and Sustainability 

Using plastic sample bags is recommended to maintain sample integrity, allowing for easy attachment of barcode fraction labels upon receipt at the lab. Hill Labs is committed to sustainability and recycles plastic sample bags through a partnership with Future Post, which repurposes suitable plastics into fence posts and other useful long-life products. 

For optimal yield and quality, make leaf testing a priority in your crop management strategy. 

For further information or assistance, contact our Ag Client Services team.  
Ph: 0508 HILL LAB (44 555 22)  
Email: ag.csm@hill-labs.co.nz