Harvesting Good Peaches and Fungicide Management

I love this time of year, as hectic as it is.  For most people in south central/central Florida – things are winding down, while in north central Florida, we are in the midst of harvesting.

Most people this year had a great season, with great fruit quality and flavor.  However, we did have a wet spring (20 inches from January 1 – May 20th) in Citra and north central Florida, while in other years we get less than 10 inches in that same time span.  Cloudy and wet weather affects a number of plant processes such as:

  • Carbohydrate fixation and accumulationaka making sugar in enough quantities to have good brix content in the fruit.  I also saw overripe fruit because growers were waiting for the fruit size to get bigger, but because perhaps of the cloudy/rainy spring, cell division (stage 1) of fruit development wasn’t as good as it has been in years past.  It didn’t help the fruit quality in the store – and this was the result:

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  • Wet feet – in orchards that have poor drainage, you can have problems with leaf drop and/or fruit drop due to damage in the root systems due to suffocation of the roots (anoxia).
  • Increased disease pressure – We also saw a bit of anthracnose ripe rot and botyrosphaeria rot in the fruit after the rains and some of the warm weather we had in the late part of April/early part of May.  It’s important that if we do have successive rain events that you apply fungicides and rotate the chemistries to avoid resistance.  Common fungicides like Abound and Topsin-M are great, but are categorized as medium or high risks for resistance and should be used sparingly or in a diverse rotation of chemicals.

Fungicide management is easy to do – but if you don’t know what a FRAC code is (and no – Battlestar Galactica fans, I’m not swearing…) here is a website that will take you to the codes for each chemical.  http://www.frac.info/publication/anhang/2014%20FRAC%20Code%20List.pdf.  You’ll notice that this chart does not have the company (trade) names of the chemicals so you will have to READ the LABEL to find out what chemical your fungicide contains – and the FRAC code should be listed there as well.

Hints for Next Season

At our winter field day this year in Fort Pierce (typically held the 2nd week of December) we will be talking about thinning.  There was a lot of small fruit put into local supermarkets, and much of this can be alleviated especially in UFSun with more aggressive thinning.  Instead of 6″ between each fruit as is suggested with other Florida peach varieties, UFSun should be thinned to 9-12″ between each piece of fruit.  In addition, anything that can be done to encourage leaf area expansion will be key to getting good fruit size and flavor development.

The use of hydrogen cyanamide is looking promising for peach growers that are down south especially as it appears to help with leaf emergence – an important stage of growth to help fruit develop its maximum potential for fruit size and good flavors.  However, we need more research on timing, and I have some key growers set up around the state this year to look at a couple of different timings and see what the impact is on leaf growth and fruit size/harvest date.  If we can get more uniform leaf emergence and bloom, then we should be able to narrow our harvest window and minimize the number of pickings necessary to harvest the entire crop.  More research to come in 2014-2015!

As always, if you have any questions – please call or email me!

Mercy

 

Bloom and Fungicide Sprays

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As we head into full bloom and early fruit set for the growers down south, please don’t forget about application of your fungicide sprays to combat peach scab.  This, along with peach leaf rust, are our major diseases here in Florida.

UFSun fruit
Peach Scab on ‘UFSun’. Notice scab lesions around the stem area where sprays were difficult to get in.

Please check the latest version of the Southeastern Peach, Nectarine, and Plum spray guide for options.  Please also pay attention to the suggested spray material choices, such as Captan and sulfur.  Sulfur is a good choice for this time of year, because it is relatively inexpensive and does a great job to cover the young fruit and protect it.  The downside is that it has a shorter efficacy length, meaning that you will have to spray more often than if you used a synthetic chemical like Captan.  Additionally, as we head into the bloom period and leaves begin to push open on the tree, be sure to begin your fertilization and irrigation regimes.  We still can get some rain during this time of year, so take that into consideration when you set up or run your irrigation programs.  For help on irrigation requirements, you can check the FAWN site for information on the evapotranspiration (ET) for the day or week.  Although we do not have an irrigation scheduler for peaches at this point, there is a citrus irrigation scheduler that may be helpful.  However, some growers are cutting the recommended amount for irrigation to peaches by various percentages according to their soil type and tree response.

A group at UF have a project in conjunction with the SWFWMD to investigate peach irrigation and reduction of water applications after harvest.  We are working with growers to establish best management practices for irrigation management, knowing that the afternoon thunderstorms often rolling through in June, July, and August can stymy our plans.

As always, be sure to let your county extension agent or myself know of any questions you have!  We are here to help.  Good luck and enjoy the beautiful blossoms!