Inking on Peach Fruit

Hello all,

I’ve had a few e-mails and phone calls about inking on peach fruit harvested in the past two weeks. Clemson University has a good publication with pointers to avoid inking – although I have to say, we do not know what causes inking on fruit surfaces.

One cause may the rainfall that we have had – which may have washed chemicals onto the fruit that have high amounts of metals (including micronutrients!). Also, precipitation/overirrigating near harvest can increase the water pressure (turgor) in cells, but this also makes them more vulnerable to abrasion damage during harvest/transportation and then anthocyanin accumulates causing what we know as “inking” in spots.

Here is a link to the article from Clemson: http://www.clemson.edu/extension/horticulture/fruit_vegetable/peach/diseases/inking.html

Research from California indicate that not only do some chemicals with high metal contents have higher incidences of inking, but so does abrasions on the skin surface. These might be from harvesting, wind damage, or abrasions in harvesting.

http://bit.ly/1zHx3IF

A couple of culprits that might have been issues this year may be Imidan and Elite (tebuconazole), although with Elite, I am watching my own research orchard, as this was my last spray on Saturday. However, we are very far behind everyone else in the throes of harvest and are about 2-3 weeks away from harvest, so we may not see much inking on the skin surface.

Steps to Avoid Inking:

Near harvest, choose chemical applications carefully.
- These chemicals have high metal contents –
  - Foliar nutrients: Micro Plex (Fe)
    Insecticides: Imidan (Al), Delegate (Al)
    Miticides: Vendex (Fe and Al), Acramite (Fe and Al), Omite (Al)
    Fungicides: Elite (AL)
    Additives: none
Don’t apply foliar micronutrients within approximately 21 days of harvest to avoid having metals on the fruit surface (e.g., copper, iron, aluminum) that have been implicated in inking.
Check the pH of your irrigation/spray water. Water with acidic characteristics (<6.5) can exacerbate inking due to increased iron availability.
Don’t overwater near harvest, as this can damage cells in the skin and cause anthocyanin accumulation, leading to inking symptoms.
With orchards that have a history of inking, leave harvested fruit in cooler for 48h prior to packing to observe inking symptoms; remove before packing.