March 2016

 

This information comes from a meeting I attended where Ken Johnson of Oregon State University gave a talk about fire blight control using organic products.  While the products mentioned below are certified for organic production, the control timing applies to both conventional and organic systems.

 

Pear:

  • Green tip – Copper @ 5-6#/ac

  • Bloom – Blossom Protect + Buffer Protect (twice)

  • Full Bloom to Petal Fall – Serenade Optimum every 2 – 5 days.  Adding 2 – 3 qts of Cueva/ac will improve control.

 

Apple:

  • Green tip – Copper @ 5-6#/ac

  • 20% & 70% Bloom -  lime sulfur + oil  (thinning sprays)

  • Immediately after 2nd thinning spray – Blossom protect + Buffer Protect (twice)

  • Full Bloom to Petal Fall – Serenade Optimum every 2 – 5 days.  Adding 2 – 3 qts of Cueva/ac will improve control.

 

Miscellaneous fire blight thoughts:

  • Most fire blight populations don’t explode until late in the bloom period.  Often it’s straggle bloom that causes the problem.   The take home message is to not slack off protection late in the bloom.

  • Early copper applications push fire blight development back to a later period where there’s less bloom present.

  • Interpretation of a “wetting period” depends on where you grow.  It can range from a rain to a heavy dew.

  • Daily highs of 70 ͦF  pose a moderate risk,  80 ͦF means a high risk of infection.

  • Orchard age is a factor to use in your program.  Older trees can stand a bit of blight.  Young trees call for a more aggressive program. 

 

The link below will take you to the presentations from the Mid-Columbia Cherry Day meeting held last month in the Dalles Oregon.  Lots of good information!

 

 http://extension.oregonstate.edu/wasco/2016-mid-columbia-cherry-day

 

 

Need more to read?  The web address below will link you to the presentations from the 2016 Bio Controls conference I just attended in California.  It was an interesting mix of industry folks.  Growers (conventional & organic), extension, manufacturer representatives, and researchers.    Biocontrol is a process that takes on a number of definitions.  It’s far more than inserting beneficial bugs into an orchard or greenhouse.  It’s equally at home in both conventional and organic systems.

 

It’s foundation is IPM, taking a preventative long term approach.  Biocontrol and Beneficial’s are a part of the solution, not the solution.   A number of factors like varietal selection, fertilization, pest, and timing of intervention influence the outcome.

As one talk wrapped up I looked back over my notes from the presentation.  Certain words jumped off of the page in my thoughts.

 

  • Perception is it’s an all or nothing system, either biocontrol or pesticides.

  • Chemicals work! (Remember, the discussion involved both conventional and organic).  It’s hard to get biocontrol’s to be effective.

  • Consumer concern is the driver behind biocontrol adoption, even though ignorance is abundant.

  • How do we “preach” agriculture to educate the public, the next generation, the great masses scrolling through Facebook?  They believe the first thing they read, “like” it and change their buying habits!

 

So here’s the link to the presentations:

 

http://www.cvent.com/events/2016-biocontrols-conference-expo/custom-36-b0d143acc44f415cb04e1ad3e3a8f2dd.aspx?cpc=HDNGMXMCBM2

 

Spring seems to be moving right along, and dormant oil is on our minds!  Timing and using the proper materials are critical to obtaining optimum control in your orchard.  Often, the question is asked “How cold is too cold to spray dormant oil?”   The text book answer is 45°F.  A bit of common sense also figures in.  Is the temperature on the rise, or decline?  Is it windy, damp, cloudy, etc.  Pay attention to freezing temps during the 48 hour period before application and for 24 – 48 hours after.  Having said all of that, remember that we farm in Colorado, some days you just have to push the envelope a bit. 

 

Horticultural oils have been in use for over a hundred years.  They are a unique tool in our arsenal from the perspective that no pest species has ever developed resistance to them. 

 

Brought down to simplest terms, the results one will obtain with oil sprays are governed by three basic factors:

 

  • the oil used,

  • how well it is applied

  • when it is applied. 

 

Oils cover insects with a suffocating film that kills both larva and eggs by a mechanical interference with the normal gaseous exchange.  Coverage is essential!

As eggs get closer to hatching they become more susceptible to killing with oil.  Research shows that oil sprays applied at the begging of hatch using a lower percentage of oil concentration are just as effective as earlier applications at a higher concentration.  Timing is essential!

So what’s the point?  We need to know what our target is and when it’s most vulnerable. Whether it’s Green peach aphid, European red mite, or Pear Psylla, missing the optimum timing by a week can make a significant difference in control. 

 

OK, so what’s the optimum timing?

 

  • Two Spotted Spider mite:  This critter overwinters as an adult female that emerges about the same time as leaf emergence.  Delayed dormant on peach and tight cluster on apple are the best timing.

  • Pear Psylla:  Pear psylla overwinters as an adult.  A large portion of the population exits the orchard to overwinter on surrounding vegetation.  They return to the orchard in the spring to mate and lay eggs.  The purpose of oil in this program is TO PREVENT EGG LAYING.  Research shows that proper timing can suppress egg deposition by as much as 50% and delay it for three to five weeks.  Time sprays at the beginning of egg laying. 

  • Green Peach Aphid:  Overwinters both as eggs and adults.  Hatch occurs before bloom.  Time sprays for delayed dormant period.

 

 It's common to make an application with a tank mix of several different pesticides and formulations.  There's a specific mixing order that will help keep you out of compatibility problems.  1) soluble packets, 2) wettable powders, or water dispersible granules, 3) flowables,  4) emulsifiable concentrates, 5) oils.  Always , Always , Always add oils last!

 

Spring is the most stressful time of the year for any fruit tree.  Your orchard is drawing from reserves as it progresses through bloom.  Soil temps are cold and limit nutrient availability.  Fruit size is partially determined by the number of cells each fruit contains.  Cell division occurs immediately after bloom (from 14 to 28 days) when stress is at it's  peak.  Healthy, well fed, trees are better able to handle and size large crops, survive winter injury, and pull buds through spring frosts.  Next years’ flower buds will be developed this season.  Keeping a tree well fed is a year round program.  Properly timed foliar applications of nutrients can help relieve the stress!

Delayed dormant: Zn, Mg & B;  Pink, Petal Fall & Summer: N, P, K, Zn, Mn & CA;    Fall: Zn, B, & N

 

“A government which robs Peter to pay Paul can always depend on the support of Paul.”

- George Bernard Shaw

 

Are pests resisting your management? -  An individual organism's genes determine its physical and behavioral traits. When individuals reproduce, they pass along unique combinations of genes to their offspring. Different environments favor individuals with different physical and behavioral traits. Individuals with genes that improve their survival will be more likely to pass along these genes compared to the rest of the population. The mix of genes in a population is called the gene pool. The composition of the gene pool continually changes over time through a process called natural selection.

 

Repeated use of the same class of pesticides to control a pest can cause undesirable changes in the gene pool of a pest leading to another form of artificial selection, pesticide resistance.

 

When a pesticide is first used, a small proportion of the pest population may survive exposure to the material due to their distinct genetic makeup. These individuals pass along the genes for resistance (survival) to the next generation. Subsequent uses of the same pesticide increase the proportion of less-susceptible individuals in the population. Through this process of selection, the population gradually develops resistance to the pesticide. (Excerpt from Fruit Crop Ecology and Management )

 

The practice of “resistance management” is an endeavor that each of us should be involved in.  As we plan our pest programs (both insect and disease) we need to pay attention to a few key components.

 

  • The class or group of chemistry a material belongs to.

  • The number of times we use it against a pest, are we using the same class of material against succeeding generations of a pest. 

 

The goal is to avoid “selecting out” any pest group by doing the same practice over and over.

All pesticides have been grouped by their class of chemistry and assigned a group number by FRAC (fungicide resistance action committee) or IRAC (insecticide resistance action committee).  Pesticide labels now contain the group or class number for each product on the label right above the name.

 

Asana, Danitol, Warrior and Ambush all belong to the same class of insecticide known as Pyrethroids.  Changing from one of these products to another will not help you with resistance management.  It’s not enough to change names, you have to change classes. 

 

The same issue is true with fungicides, it’s important to have a thorough understanding of the types and capabilities of the fungicides you use to manage plant diseases. Using the correct fungicide at the right time in the proper amount can often mean the difference between a clean, high quality crop or a significant loss in yield or quality.

 

Don't let powdery mildew catch you flat footed.   Control is best obtained early in the season, not once you notice it!  Cherries are best treated by starting at petal fall & shuck fall; peaches from bloom to pit hardening and apples before bloom.  There's a wide selection of materials with various modes of action available.  Don't fall into a rut and build resistance in you orchard.  Rotate classes of materials and start early!

 

“The higher you go in life, the fewer people there are to offer honest feedback

or restrain your unpleasant traits.”  - George C Marshall

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