Praise the Rain, Pass the Fungicide

Although, it's probably too late for the fungicide to correct Citrus Brown Rot 

and Septoria on coastal lemons. 

In normal rainfall years, a skirt spray of copper is done to prevent rain splash bringing spores of various Phytophthora species in contact with fruit.  The spray is done the fall especially if high rainfall is expected that year, and can be reapplied in January/February if indeed rain has arrived.  The spray is usually only up about 4 feet from the ground, rarely needed above that.  But this year, there has been lots of wind and brown rot has appeared throughout tree.  There has been lots of wind to spread the spores and create disease in fruit quite above ground level.  Fruit on these trees is going to need to be selectively picked to avoid the infected fruit, adding to harvest costs.

https://ipm.ucanr.edu/agriculture/citrus/brown-rot/

Septoria is less common than brown rot along the coast where a skirt spray is or used to be normal practice.  This was before the drought and low lemon prices made the practice less common.  In the case of septoria, a whole tree copper spray is recommended in the fall.  The disease, although not unseen, is not common, so most growers would apply only a copper skirt spray for brown rot.  With this 2023/2024 rain year, the disease has showed up in many orchards, and of course, it is above the brown rot spray line in the canopy.

https://ipm.ucanr.edu/agriculture/citrus/septoria-spot/

Both of these diseases are going to cause problems for growers, because once in the fruit, it's not treatable or salable.

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