Protecting Your Apples From Secondary Apple Scab

Season-long control of apple scab is very difficult if primary apple scab infections develop.  Primary scab infections appear with brown puffy like lesions on the top side of the leaf (A) and as mold like lesions on the bottom of a leaf (B).

 

Fig. 1

 

 

These primary lesions  produce secondary inoculum placing fruit at risk for secondary, conidial infections (Fig. 2).   Once the  primary ascospores have matured at least 95%, and are possibly depleted, we will have to continue to monitor scab infection events and maintain spray coverage accordingly for at least 14 more days, if not longer, if we we have found primary lesions,  to protect from secondary lesions like those in Fig. 2 on McIntosh and any McIntosh hybrids like Cortland and Empire.  If you have seen lesions like those in Fig. 1 or Fig. 2, on your trees or on your fruit, then you will now need to protect the rest of your clean from secondary lesions.

Fig. 2

 

The best product for protecting your fruit is Captan, a contact protectant. And that means that your trees will need to be sprayed with Captan at the full labelled rate prior to any rain event to protect your fruit.  If there are no rain events between sprays, a single contact protectant spray will last at least 10 days but not more than 14 days, based on the product's labeled information.  You will need to make sure that your trees and fruit are protected prior to any rain event  when using only a protectant. But, a protectant can lose its effectivness after 2" of rain, so you also want to reapply as soon as you can before the next rain event.   If no protection is available during the wetting event, then the liklihood of your fruit getting infected dramatically increases.

As always, be sure to follow the label directions on any spray product you may use.   For further information on control of apple scab, refer to:

  http://royaloakfarmorchard.blogspot.com/2021/04/apple-scab-season-has-arrived.html

Reference in this publication to any specific commercial product, process, or service, or the use of any trade, firm, or corporation name is for general informational purposes only and does not constitute an endorsement or certification of any kind by Royal Oak Farm.  People using spray products assume responsibility for their use in accordance with current label directions of the manufacturer for that product.

 

Codling Moth Have Arrived

Pheromone lure with trapped moths.

To determine when flight begins for codling moth, commercial growers make use of pheromone traps.  Once moths have been trapped for  two consecutive days in a row, a biofix is set  that initiates the beginning of growing-degree-day calculations.  We know that at approximately 100 degree days after the biofix date codling moths begin to lay eggs and those eggs begin to hatch at approximately 250 degree days after biofix.  It is this information that aids in the timing of necessary sprays for codling moth so they do not damage fruit.  Growers wishing to time sprays based on egg development and hatch (larval stage) should make an application of an insecticide at 250 DD (base 50 degrees F) after the first sustained capture of males in the sex pheromone traps.  Here is a Detailed Growing Degree Day Model for Codling Moth.   

 

We have now established a biofix for CM for this spring and it is May 17.  Since codling moths usually do not fly on nights when the temperature is below about 60 degrees, and the predicted lows for the next week are above 60 degrees, I think this biofix is going to hold for this spring.

 

You may apply insecticides that need to be present before egg laying at about 50-75 DD or you may apply insecticides that target early egg laying period at 100-200 DD.  Since the biofix date, we have accumulated approximately 10 DD, but with the projected hot temperatures for the coming week, we will have to keep a close eye on the degree days for the first application of an ovicide.  It will soon be time time for the home grower to apply a spray to target early egg laying. 

For the home orchardist who does not have the benefit of a weather station or other means to calculate degree days, a simple tree growth stage time table can be followed.  Codling moths usually start flying at bloom time or just after bloom time at petal fall and at approximately the same time as plum curculio.  Eggs laid by these moths begin to hatch about two weeks after petal fall, depending on the weather. You can apply the first codling moth spray at this time, about two weeks after petal fall, to prevent larvae from entering the fruit. Because most insecticide residues last 7 to 10 days and moths are continuously present throughout the summer, apply a spray every 7 to 10 days to prevent later broods of codling moth larvae from entering apple and pear fruits. If using a natural product like Spinosad, then spray after every rain due to wash off.  Always follow the label directions of any spray you may use.

Several insecticides can be used for codling moth control including acetmaprid and/or spinosad.  Acetamiprid is a soft, conventional control and is available as  Ortho Flower, Fruit and Vegetable Insect Killer.  This is a ready to use product that contains .006% acetamiprid, and is also available in a concentrate containing .5% acetamiprid.  Acetamiprid is a synthetic organic compound of the family of chemicals that acts as neonicotinoid insecticides. Acetamiprid is a contact, translaminar insecticide for sucking-type insects and can be applied as a foliar spray.  Translaminar insecticides are absorbed by leaves and can move through the leaf to the opposite surface they contact. They are not truly systemic and do not move throughout the entire plant. Acetamiprid acts on a broad spectrum of insects, including aphids, thrips, plum curculio, apple maggot and Lepidoptera, especially codling moth.  When sprayed in the evening at sunset, it will not harm bees or other beneficial insects once it is dry. Be sure to follow all label directions on the bottle for proper application.

An all natural approach is also available in the form of Bonide’s Captain Jack’s Dead Bug Brew.  Captain Jack's Deadbug Brew® contains Spinosad (spin-OH-sid), a product first isolated from a naturally occurring soil dwelling bacterium that was collected on a Caribbean island from an abandoned rum distillery. Deadbug Brew® kills bagworms, borers, beetles, caterpillars, codling moth, gypsy moth, loopers, leaf miners, spider mites, tent caterpillars, thrips and more! Use on fruits, vegetables, berries, citrus, grapes, nuts and ornamentals and approved for organic gardening.  

Both of the above products will kill Codling Moth larvae and need to be sprayed just prior to the emergence of the larvae,  which is between 100 to 250 DD after biofix.  Since we are not yet at or near 100 DD after biofix, your trees can be sprayed in about 7 to 10 days, depending on the amount of rain that may fall at night between now and then.  Typically after 1" of rain, these sprays will have been washed off and will need to be sprayed again to be effective.

For additional information, see the following fact sheets which are available from local university extension services:

https://ecommons.cornell.edu/bitstream/handle/1813/43086/codling-moth-FS-NYSIPM.pdf

http://extension.psu.edu/plants/tree-fruit/insects-mites/factsheets/codling-moth

 Reference in this publication to any specific commercial product, process, or service, or the use

of any trade, firm, or corporation name is for general informational purposes only and does not

constitute an endorsement or certification of any kind by Royal Oak Farm.

People using spray products assume responsibility for their use

in accordance with current label directions of the manufacturer.

Time to Plan For Plum Curculio

Plum Curculio Ovipositing Egg

With apple scab season in our midst, and petal fall coming to an end, it is time to turn our attention to several insect pests. Plum curculio (PC) is one of the most difficult insect pests to contain.  They enter the orchard from the perimeter after the adults pass the winter hidden under leaves, along fence rows, in brush piles, rock walls and in other protected places. In spring when the weather warms up (mean temperature 60°F. or maximum temperature above 75°F.), about the same time apples are blooming, the adults become active. The adult plum curculio beetles, pictured to the left, emerge right around or just after petal fall, to feed on apple buds, flowers, leaves and young fruit.  The duration of full bloom to petal fall is usually about 5 to 10 days.  From petal fall to fruit set is generally another 5 to 10 days, depending on temperatures.  Once the fruit sets, female beetles cut holes in the young fruit and deposit one egg in each cavity. 

 

 

These sites, called oviposition stings, are easily identified by their crescent shaped cuts. Unlike codling moth, the larvae of plum curculio rarely cause damage to the fruit. The fruit is primarily damaged superficially by the egg-laying and feeding by the adults. These "stings" will cork over and cause an indentation in the fruit as it matures making it look deformed and unsightly.

The question then becomes, how do we control them??  Pesticide application at this time is very important for plum curculio control. To prevent fruit drop, and due to toxicity to bees if there are still blooms on the trees, do not use carbaryl (Sevin®) or any pyrethrin based spray as these are highly toxic to honey bees and other pollinators as well as any beneficial insects. Any other pesticides should be applied int he evening when the honey bees have returned tot heor hives.  For home growers, an acetamiprid spray such as Ortho® Flower, Fruit & Vegetable Insect Killer Ready-Spray is a deterrent.  If no blooms are present  on any trees, a pyrethrin based spray can be used as a deterrent, even though there may be no fruit.  Picking up and disposing of any fallen fruit will reduce problems with plum curculio, other insects, and many plant diseases. For conventional growers, Avaunt or Assail are two choices you might use, based on your codling moth protocol and your apple maggot protocol.

For a pure organic spray, the two most frequently used insecticides are Surround® and Pyganic®, both certified organic. The organic products may need to be sprayed multiple times for complete control at 7 to 10 day intervals or after any rain. And, as always, follow all label directions on any spray product. 

For a complete Fact Sheet on Plum Curculio, consult the Cornell University Plum Curculio Fact Sheet and for an in depth look at this pest.
__________________________________________

This publication contains pesticide recommendations that are subject to change at any time. These recommendations are provided only as a guide. It is always the pesticide applicator's responsibility, by law, to read and follow all current label directions for the specific pesticide being used. Due to constantly changing labels and product registration, some of the recommendations given in this writing may no longer be legal by the time you read them. If any information in these  recommendations disagrees with the label, the recommendation must be disregarded. No endorsement is intended for products mentioned, nor is criticism meant for products not mentioned.  The author assumes no liability resulting from the use of these recommendations.