It wasn't supposed to rain this winter, but it did. The forecast was for La Nina which typically brings less rain and would continue the drought pattern we have had for the last three years. So with no rain, there is no need to spray a protective copper for brown rot or septoria, right? And with low prices for lemons, it pays to save money, right?
Well it did rain and we have had some problems. There have been problems, as well from the violent winds and the cold weather. According to Daniel Swain at Weather West, this was the coldest winter on record, even though the amount of time below freezing was low. The wet weather brought down trees and flooded fields, burying trees in some cases.
So we had unexpected rain, and violent winds and cold weather and that has led to concerns about the lack of copper applications. And there have been calls concerning symptoms on fruit that kind of look like disease, however in many cases it is not disease that is the ultimate cause of the damage. So let's look at some of this damage.
If copper had been applied, brown rot (Phytophthora sp.) probably would not have resulted from rain splash from the ground onto the fruit. There was a heck of a lot of mandarin and oranges that were lost in one case because of this.
In a few other cases, we have seen septoria fungal spot due to the fruit staying wet too long. Finding the black structures can identify this problem
But a lot of fruit spotting that might be associated with disease causing organisms, is actually abiotic, caused by non-living sources, like
Hail
Puncture
Oil spray damage
Cold, wet conditions that may have been on the edge of freezing.
So, it was a wet winter. Blustery and cold. It would have helped in some cases to have had copper on, but there were other causes of fruit damage than just all that wet. Some growers regret not having just put it on as part of the regular regime. This coming year, it's time to get regular again and make sure the trees have a protective copper cover. But if the rain and cold and wind and hail are back, there are some things that are a lot harder to provide protection for.