[Fruit garden](https://dunger.ua/en/blog/categories/fruit-garden) # How to diagnose grapevine chlorosis and decide what to do Published 2026-11-11 Updated 2026-11-11 To read 7 min Compare young and old grape leaves, inspect the root zone and irrigation, and choose the right samples before treating yellowing. When grape leaves turn pale between their veins, check the age and position of the first affected leaves before reaching for fertilizer. Green veins with pale tissue in between are a pattern called interveinal chlorosis. The pattern can guide an investigation when you combine it with other observations. Young leaves near a shoot tip and older leaves at its base can lose colour for different reasons. Compare the affected vine with a healthy one, check water around the roots, and decide what samples a laboratory needs to help find the cause. ## Find where the colour change first appeared ### Young leaves near the shoot tip Pale tissue between the veins of the youngest expanded leaves can be consistent with poor iron availability. Alkaline soils, including calcareous soils, may contain iron that roots cannot take up readily. You cannot measure its availability from the colour of one leaf. Note whether the change affects all tips or only one shoot, and check if other vines in the same part of the row show a similar pattern. Compare leaves of a similar age on healthy and affected vines. A very new leaf can differ in colour from an older one even on a healthy plant. If only one shoot changes, follow it down to where it joins the rest of the vine. Check for a break, rubbing against a support or a tie pulled tight around the stem. If you see the same pattern on nearby shoots, mark how far it extends along the row. ### Older leaves near the base Magnesium is one possibility when older leaves change first and new leaves stay green. In some red-fruited cultivars, the areas between veins can turn reddish instead of yellow. A shortage of potassium can also change leaf colour, often starting at the edges. Leaf edges can brown in drought, very wet soil or after spray injury as well. These differences help decide what to test. They cannot reliably identify a nutrient shortage from a photograph. ## What to record before taking samples - The date, growth stage, cultivar and rootstock if known. - Which leaves changed first and where they sit on the shoot. - Whether colour loss is between veins, at the edges or across the whole blade. - Which vines are affected and whether they share a low spot, irrigation line or part of the row. - Rain, a change in irrigation, fertilizers or sprays used before the symptoms appeared. ## Inspect the root zone and irrigation separately Sketch the row and mark downspouts, low spots, paths and emitters. Then mark the vines with symptoms. If affected plants are clustered in a hollow, check the soil after rain. If only the end of the row changes colour, check whether water reaches those vines at the same rate as the others. A dry-looking surface can cover wet soil. In other places an emitter may wet a narrow strip and leave much of the root zone dry. Inspect small areas without digging across the entire root system. Compare soil around a healthy vine with soil around the affected one. Note where the soil stays wet or dries quickly, and record any recent construction or trench work. Tell the laboratory if one end of the row received a new layer of soil. Combining samples from unlike areas could hide the difference you want to measure. Vines of different ages and rootstocks can share a Ukrainian home garden. An older vine beside a wall may receive runoff that a younger vine in the middle of the yard does not. Compare the same cultivar and a similar age where possible. If you cannot find a close match, record the differences. Use the guide to recognising leaf chlorosis to understand the pattern in other plants. Diagnose the vine here by tracing the affected leaf position and the root conditions. ## Choose tests that help separate causes Ask a laboratory how to sample soil beneath a vine and whether to test carbonates along with pH. Soil pH helps explain the conditions for iron uptake. It cannot confirm that iron is responsible for the colour change in a particular vine. Keep samples from affected and unaffected areas separate when the aim is to compare conditions. Label them by location and record any differences in drainage, irrigation or previous soil work. For a plant sample, ask whether the lab needs leaf blades or petioles, which leaves to take, and at what growth stage. Put the affected and comparison samples in separate labelled containers. List recent sprays because residue can affect how a result is interpreted. Total iron measured in a leaf does not always correspond to the severity of iron chlorosis. Consider the result alongside leaf age, soil properties and the moisture conditions around the roots. ## Make a decision using the observations - If symptoms cluster where water stands after rain, investigate how the water reaches that spot and avoid adding irrigation to saturated soil. - If young leaves of several vines become pale between veins in alkaline soil, discuss iron availability and the rootstock with a diagnostician. Wait for evidence before changing soil pH. - If older leaves change first, ask about checking magnesium and potassium. Applying potassium without a confirmed need can make a magnesium problem harder to manage. - If a single shoot is affected or individual spots or unusual distortion appear, take a full plant photo and clear photos of the leaves for diagnosis. Imagine that two vines in a hollow develop pale tips after repeated rain, while the same cultivar uphill keeps its usual colour. Mark both areas, check how wet they are, and ask about separate soil samples. After you improve irrigation or runoff, compare the next expanded leaves with the earlier photos. New foliage with typical colour is useful evidence for deciding how closely to keep monitoring the area. One observation on its own cannot settle the cause. Make a separate feeding decision if the test identifies a nutrient need. Record what has already been applied and read the exact crop and application stage on the product label. Review [spring feeding for grapevines](https://dunger.ua/en/blog/spring-grapevine-feeding) when planning the next eligible season. A vine showing yellow leaves this week may need better drainage, further diagnosis or a product targeting a different issue. ## Potassium for a separately verified grapevine need [](https://dunger.ua/en/mineral-fertilizers/small-packaging/for-garden-plants/28-complex-fertilizer-for-grapes) ### [Complex fertilizer for grapes](https://dunger.ua/en/mineral-fertilizers/small-packaging/for-garden-plants/28-complex-fertilizer-for-grapes) This granular product contains potassium and sulphur. Consider it only if testing independently confirms that the vines need potassium. The directions specify early spring before leaves open. Finish investigating any unexplained interveinal yellowing before deciding to feed. The product page lists 1 kg and 5 kg packs. Read the full directions and measure the area where the need was confirmed before choosing a pack. [Plan your growing area in My Garden](https://dunger.ua/en/my-garden) ## Frequently asked questions ### No. Start with leaf age, root conditions and the distribution of symptoms. With young leaves affected first, check conditions for iron uptake. With older leaves affected first, consider looking at magnesium and potassium as well. ### ### ## Rate this article No ratings yet. Be the first! Rate this article ## Discussion(0) This discussion is shared across all article languages. 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