Yellow Leaves on Hazelnut trees

[Cedric Lefebvre]

1. Need some advice. Growing a hazelnut orchard inoculated with black winter truffle spore. Orchard is irrigated properly, pH is 7.5. Trees are about 4 years old and appear healthy, except 12-15 trees have developed yellow/brown leaves with some black discoloration. Trunks and branches look fine – no cankers or stromata. Not sure what this is – disease, nutritional deficiency or other? Looking for advice on pruning browning limbs, removing trees, treating with anti-fungal product, other intervention? Thanks for any advice!

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[Todd Maveus]

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Hi Cedric,

We are not the experts, but just wanted to share that we had similar concerns about our oak trees having leaf browning when they were about 4 years old.  We had taken a pruning class through our local agricultural extension office and reached out to them.  They put us in touch with the Plant Disease and Insect Clinic at North Carolina State University.  We initially sent them photos, but they also requested a physical sample, which we sent in.  For $20, we got a report back from them in about a month’s time (late August to early October) that helped us better understand the impact of disease and insects on our tree health and helped to ease our concerns, so we highly recommend engaging with your local extension agent.

Sample of the results we received:

Three diseases were found on the submitted branches/foliage, and were present on all three subsamples. The dark spots, often along veins, are Tubakia leaf spot. This is common on oak. The spots often enlarge late in the year as the leaves begin to senesce. The yellow blotches with white patches (esp. on the underside) are powdery mildew. Neither the powdery mildew nor the Tubakia leaf spot represent a significant threat to the health of the trees. The third disease is thread blight, caused by the fungus Ceratobasidium ochroleucum, formerly known as Corticium stevensii. This is causing death of groups of leaves, starting at the leaf bases. It is not killing the cambium, but could cause extensive leaf damage under wet conditions.

We do also experience yellowing leaves on our hazelnut trees (attaching a picture in case a comparison is helpful), but not quite to the degree that your picture shows.

We do spray our leaves with Sevin as needed for insects and our oak trees with milk for mildewing as needed but have not yet tried any anti-fungal products or nutritional additives other than planting clover for a few seasons to improve our soil’s nitrogen.  We leave the heavy pruning for late fall/winter season, but we do spot prune unhealthy branches as we encounter them, and we have had to remove some unhealthy trees here and there. Our orchard is about 8 years old now and we did get our first small winter truffle harvest this past February!  We wish you the best and hope that you find the solutions that you need.

Blessings,

Missy and Todd

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