Sunday, March 24, 2013

Critical Temperatures for Fruit Buds

   Temperatures are predicted to go down to 20 to 21 F tonight and the next night.  Thankfully, the colder weather of the last few days slowed the development of fruit buds.  All the fruit trees have swollen fruit buds now, but bud development has not yet progressed to the pink stage on peaches, green tip on apples, or bud burst on pears.  If buds had progressed to those stages, the temperatures predicted would have eliminated this year's peach crop and hurt the pear crop.  
   Fruit buds are extremely cold-hardy while dormant.  Peach buds can withstand winter temperatures down to -10 F without damage, and apple and pear buds can take winter temperatures down to -20 to -30 F, depending on the variety.  Once fruit buds start to grow in spring, they progressively lose cold hardiness as they develop.  They are most vulnerable to freezes at bloom and post-bloom.
Our peach trees are thankfully still in the swollen bud stage, so the peach crop shouldn't be hurt by temperatures predicted to go down to 20 to 21 F over the next two nights.
   At the swollen bud stage where they are now, peach fruit buds would suffer about 10% bud kill if temperatures drop to 18 F, and 90% bud kill if temperatures drop to 1 F.  Apple buds at the silver tip stage would suffer about 10% bud kill if temperatures drop to 15 F, and 90% bud kill if temperatures drop to 2 F.  Pear buds at the swollen bud stage would suffer about 10% bud kill if temperatures drop to 15 F, and 90% bud kill if temperatures drop to 0 F.
   So thankfully, this freeze should not hurt our fruit crops.  We still might have frosts in the next 3 weeks that could hurt the tree fruits while they're blooming, though a light frost down to 28 F and no lower during bloom is actually beneficial, so we don't have to do so much fruit thinning.
Just a week ago we had temperatures in the 70's and were pruning peach trees.  Our son Michael helped with this while home from college on spring break, as did our other workers.
   All the small fruit crops bloom later, so aren't usually hurt by frosts.  Usually I would have removed the winter mulch from the strawberries by now, but the cold March kept new leaves from growing, and thankfully I left the mulch on the strawberries until now, which insulates the fruit buds against the cold.  The early 'Natchez' blackberries have broken bud, but the leaves grow first on blackberries and raspberries and they don't bloom until much later, usually after the frost risk has passed.
   It looks like strawberry season will start a bit later than most years, probably about May 8 or 10.  That's quite a change from last year.  We'll still have 'Enterprise' and 'GoldRush' apples for sale until early May this year.  They're protected from freezes in our sales building, and keep in top condition for 6-8 months in our cooler.  If you want to get apples (or more apples), call 620-597-2450 to let me know when you're coming.  Thanks.

Sunday, March 17, 2013

Biorational Pest Control

   Fresh fruits not only taste great, they're also very healthy foods!  Fruits are full of vitamins, nutrients, fiber and antioxidants that can help prevent heart disease, certain cancers, type-2 diabetes and Alzheimer's disease.
   Unfortunately, many insect pests, fungi and bacteria also like to feed on fruits and fruit-bearing plants.  If these pests are not prevented, every fruit can be wormy and/or diseased.  I did research on irrigation methods and pest control of apples for my Master of Science degree from North Carolina State University, and saw literally every single apple from unsprayed plots develop fruit rots.  I researched genetic resistance to strawberry fruit rots for my Ph.D. from University of Arkansas, and again saw the huge destructive impact of fungal pathogens, but also the genetic differences between fruit varieties in susceptibility to these pathogens.
'Enterprise' & 'GoldRush' apple varieties were selected to be immune to apple scab disease, so we don't have to spray for that disease.
   On our fruit farm, we practice biorational pest control.  This involves selecting disease-resistant fruit varieties whenever possible, so we can reduce or eliminate sprays for those diseases.  For example, we grow apple varieties immune to apple scab disease, so our apples need half the sprays that grocery-store apples get.  Biorational pest control also uses cultural pest control methods whenever possible, such as pruning out all diseased or dead wood and burning the prunings, so disease spores don't spread from branches to fruit.
   Biorational pest control limits the number of pest control sprays to the least amount needed, and utilizes only materials that are extremely safe for people & the environment.  For example, many of the fungicides we apply were derived from soil microorganisms and attack enzymes found only in fungi, so have NO toxicity to people, mammals or any organisms other than fungi.  We do not practice "organic" growing, which limits spray materials to those that occur naturally, regardless of how toxic they are to people & the environment.  Many people think that "organic" growers do not spray crops, but actually they must apply many more sprays because "organic" spray materials are less effective and wear off quicker.  Many "organic" spray materials are also much more hazardous to people & the environment than the biorational spray materials that we use.  
Bill just applied the first fungicide of the season to our peach orchard, to prevent peach leaf curl and brown rot.
   Studies have shown that locally-produced fruits have up to 6 times the levels of vitamins, nutrients and antioxidants as do "organic" fruits grown in the arid western U.S. and shipped halfway across the country.  Utilizing locally-produced fruit also saves fossil fuel energy, and they taste MUCH better!
   We still have many 'Enterprise' & 'GoldRush' apples for sale, protected from freezes and kept in top condition in the cooler in our sales building.  We do not apply any wax or post-harvest fungicides to our apples, as is done on grocery-store apples.  I give taste samples; each apple has its own unique flavor.  They're both wonderful for cooking & baking as well as fresh eating.  'Enterprise' apples keep well for 6 months in the fridge, and 'GoldRush' apples keep well for 8 months in the fridge.
   From Dec. 1 to May 31, we're open by appointment, so please phone a day or two before coming, and leave a message on the phone answering machine saying what day & about what time you'll be coming, so I can look for you.  We're pruning peach trees now, & can't see the driveway from the peach orchard.