Dear farmers, few sights are as painful as seeing beautiful vines drooping listlessly and failing, often signaling the cursed workings of the foulest fungus - the Botryosphaeria canker.
Caused by a variety of Botryosphaeria fungi, this curse has spread throughout the regions where grapevines grow, and poses the greatest threat to our craft. Originating from woody objects, these fungi now live on every earth that produces grapes.
As fellow grape bunch processors, we must understand the tricks of this cursed man and maintain his craft. Let's start our study by taking a deeper look at the tiny living creatures that cause the cancer disease Botryosphaeria.
What is Botryosphaeria Canker of Grapevine? What are the symptoms?
Some key facts about Botryosphaeria:
- Several species cause disease on grapes, including B. dothidea, B. obtusa, B. corticis and B. rhodina.
- Survives dormantly in infected plant material, pruning wounds or bark lesions as pycnidia fruiting bodies.
- Spores are rain-splashed or wind-dispersed to infect fresh pruning wounds or bark damage.
- Prefers warm, humid conditions but infects grapevines worldwide across a wide temperature range.
- Causes dieback of canes and cordons as well as trunk diseases leading to complete vine collapse over time.
So in summary, we're dealing with an opportunistic wood-rotting fungus that takes advantage of pruning wounds or other injuries to infect grapevines. Its ability to survive dormantly means Botryosphaeria canker poses a constant threat.
Spotting the Signature Symptoms
To catch infections early, it's important to regularly inspect vines for these telltale signs:
- Sunken, dark lesions developing at pruning wounds or other injuries that enlarge over time.
- Premature wilting, dieback and discoloration of young shoots or older canes/cordons.
- Internal brown streaking of vascular tissues visible when bark is peeled away from infected areas.
- In severe cases, entire vines may decline and die within 1-3 years as trunk infections girdle plants.
Take note - symptoms can vary depending on environmental conditions, grapevine variety/rootstock and fungal species involved. But these classic signs mean trouble's likely brewing.
Best Practices to Control and Prevent Botryosphaeria Canker of Grapevine
1. Cultural Tactics for Prevention
Some cultural practices can help suppress Botryosphaeria naturally:
- Prune during dry, non-rainy weather and disinfect tools between cuts to avoid wound infections.
- Control other diseases/insects that may stress vines and make them more susceptible to canker invasion.
- Use own-rooted vines or resistant/tolerant rootstocks whenever grafting is required.
- Maintain balanced fertility and avoid excess nitrogen that stimulates succulent new growth prone to infection.
- Remove and destroy infected/dead vine parts promptly to eliminate fungal inoculum sources on the property.
Combined with other controls, cultural practices are foundational in any integrated disease management program.
2. Fungicide Options When Needed
For commercial growers, protectant fungicides are an important tool against Botryosphaeria canker:
- Copper compounds (copper hydroxide, copper oxychloride): Multi-site contact fungicides effective against a broad range of fungi.
- Dithiocarbamates (mancozeb, maneb): Low-cost protectants, though resistance has emerged in some pathogens.
- Strobilurins (azoxystrobin, pyraclostrobin): Systemic fungicides effective at low rates but high resistance risk if overused.
- SDHI fungicides (fluxapyroxad, penthiopyrad): Newer fungicides that disrupt fungal respiration. Low resistance risk.
Always rotate between fungicide classes, mixing products or using premix combinations per label instructions to delay resistance.
3. Biological and Eco-Friendly Controls
Some eco-friendly options for organic growers:
- Trichoderma spp.: Free-living soil fungi antagonistic to various plant pathogens through nutrient competition and antibiosis.
- Bacillus subtilis: Soil bacterium with antifungal properties that may suppress Botryosphaeria spp.
- Plant extracts: Essential oils from neem, cinnamon or other plants show direct fungistatic effects against Botryosphaeria in vitro.
While still being optimized, biologicals offer a promising low-risk approach - especially as part of an integrated program. More research is needed.
4. Integrated Tactics for the Long Haul
The most durable Botryosphaeria canker control combines cultural, chemical and biological tactics:
- Start with own-rooted vines or resistant rootstocks and maintain high hygiene standards.
- Prune carefully during dry conditions and remove/destroy infected vine parts.
- Monitor for symptoms and apply protectant fungicides preventatively when needed.
- Explore biological products that induce resistance or compete with the pathogen.
- Consult experts regularly and adapt your program based on changing conditions.
With diligence, vigilance and a commitment to integrated practices, we can significantly curb this fungus's impact on our grape crops for years to come. Our livelihoods depend on it.
Conclusion
I thank you for caring for this story. Please contact me if more questions arise. Also keeping the net with farmers and advisors in the earth field - with vigilance and shift 'getting change, with fellowship we can witness the grapes of the unrelenting curse of cancer. Wishing you a full, healthy harvest throughout the season to come!
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