While the provided reference doesn't specify the exact species of green fungus that might grow on walnuts, it indicates that mold growth on walnuts is linked to several factors. Here's a breakdown of why this happens:
Causes of Mold Growth on Walnuts
Several factors contribute to mold (including green mold) developing on walnuts:
-
Sunburn: Walnuts damaged by excessive sun exposure are more vulnerable to fungal infections. The damaged outer layers create entry points for mold spores.
-
Insect Infestations: Insects can damage the walnut shell and hull, again creating openings for fungi to invade. Furthermore, insects can carry and spread fungal spores.
-
Walnut Variety: Some walnut varieties, especially those with larger openings at the stem end, are inherently more susceptible to mold. These openings provide easier access for mold spores.
-
Fungicide Timing: Standard fungicide programs focused on preventing Botryosphaeria (BOT) might not be effective against the specific molds that cause green fungus on walnuts. The timing for mold-specific sprays is often later in the season.
Why Green Mold?
Many different species of mold can appear green. Without a lab analysis, it's impossible to say precisely which species is affecting your walnuts. Common green molds include species of Penicillium and Aspergillus.
What to Do
-
Prevention is Key: Focus on preventing sunburn and insect infestations through proper orchard management practices.
-
Targeted Fungicides: Consult with a local agricultural extension agent or plant pathologist to identify the specific mold affecting your walnuts and to develop an appropriate fungicide program. Remember that the timing of these sprays is crucial.
-
Select Resistant Varieties: When planting new trees, consider walnut varieties that are less susceptible to mold.
-
Harvest Promptly: Harvest walnuts as soon as they are mature to minimize the time they are exposed to potential fungal infections.
