Defects on Toro fruit

Asked September 18, 2017, 3:02 PM EDT

Dear Extension Office, On the fruits of my Toro variety I have observed some defects. Please find included a photo of berries. I have some frost event this spring with temperatures in -2 - (-2,5) C range. If it possible this to be a reason ? or other factors are more probable reason for those ? I would appreciate your kind assistance.

Outside United States blueberries blueberry diseases

3 Responses

It is not the typical freeze injury we see on fruit where the skin has been damaged. I call them frost marks or frost rings. I attach a picture of the type of injury we see on the surface and also a picture of internal injury when the freeze occurs immediately after bloom and damages the ovaries inside the fruit.
When did you freeze occur in relation to bloom? This damage looks deeper and is only inside the calyx cup where the petal tube would attach. It looks like some type of damage occurred there and thick corky tissue formed at the surface. The fruit cracked later as it grew because the corky tissue could not expand.

Hello,

The frost occurred at early bloom. A large part of the fruits have also not throw of the petals. Dried brown petals have stick out of blue fruits at harvest. Fruits with petals did not however have such a corky tissue. Could this be nutrition related disorder or perhaps related to some kind of spray damage?

Blueberries have been sprayed with foliar N,P,K base fertilizers, pristine, iprodion, captan, and switch fungicides only thaicloprid based insecticide have been used. Perhaps this could be an useful information. Perhaps You have observed such fruit phenomenon before ?

Many thanks for Your kind assistance.

No I have not seen this particular symptom before. It could be freeze injury but as I said I have not seen it before following a freeze, and we commonly have freezes during bloom. Having the petal tube damaged and adhering to the fruit is common after a freeze but most of that fruit is not pollinated and falls soon after bloom. It does not resemble spray injury which usually occurs on the outside of the fruit, not in the calyx cup. So I have to conclude that this injury was probably related to the freeze, but I do not know the exact mechanism.