Strawberries
Raspberries
Blueberries 
Preventing Spray Injury
Meetings

Strawberries: The May 17-18 long weekend was cold and frosty. Many growers protected strawberry bloom and buds with irrigation; damage ranges from light to significant. Remember that in order to protect against frost, water must be continually freezing during the frost event. See Irrigation for Frost Protection on the OMAFRA website. 

Strawberry bloom is susceptible to infection from Botrytis, and even more so after frost damage. Apply fungicides at 5-10 day intervals during the boom period in strawberries. Use the shorter interval if weather is wet.  Because other diseases will be showing up soon, such as anthracnose, common leaf spot, and powdery mildew, it is good include some broad spectrum fungicides in your program, such as Captan or Maestro, Pristine and Switch. Use Pristine or Switch when disease pressure is high. These products include more than one active ingredient and are very effective. 

Bacterial angular leaf spot started to show up early last week.  It is evident on lower leaves and will spread with rain or irrigation to new growth and calyces. 

This is a critical time for clipper weevil control where it is present. Scouting pays off for this pest as it is not a problem in all fields. Very little damage has been reported so far, but this pest will be very active during the warm weather at the end of this week. Watch for damage along the edges of fields, and especially in older fields.  It is too late to apply Furadan if any bloom is present; this is very toxic to bees and also affects calyces of Annapolis and Cavendish. Pyrethroid insecticides (Ripcord, Matador, Up-Cyde and Silencer) can be used now to control clipper weevil and tarnished plant bug. Thiodan is not the best for clipper weevil, but when used for plant bug, can be expected to have a short term effect on clipper weevil as well. 

Tarnished plant bug nymphs have been found in many regions and populations will reach threshold quickly now. Check all blocks with bloom or green fruit for small green, active plant bug nymphs. A good technique is to shake blossom clusters onto a paper plate and watch for insects that fall onto the plate. 

Strawberry plants should be growing now and leaves extending fully. If your strawberry plants seem to be “going backwards”, check for the following problems:  

• Winter injury                          
• Root weevils                          
• Red stele                          
• Cyclamen mite 

Cyclamen mite problems are showing up in almost every field I’ve seen this week. Affected plants are stunted and slow to grow. The problem may be showing up in patches, with nearby plants taller and normal, while adjacent plants are short and stunted. New leaves are small and sometimes thickened or roughened. To diagnose this problem, pinch out the newest, unfolded leaves in the crown, and use a strong lens or microscope to look for mites along the mid-vein of the leaf.  This pest needs immediate attention. Thiodan applied in a high volume of water will do a good job. Be sure to use the rate for cyclamen mite control, not plant bug control. For cyclamen mite, use Thionex 50 W at 4kg/ha or Thiodan 4EC at 5L/ha.   

Figure 1: Plants stunted from cyclamen mite

Figure 2:  Cyclamen mite feeding causes roughened puckered leaves

Figure 3:  Pinch out new leaves to look for mites along veins

Figure 4: Cyclamen mite and egg much magnified

 Raspberries:  Crop development ranges from buds emerging to first bloom. Fungicides are important to protect against cane diseases. Apply at least two fungicides before bloom, ensuring good coverage of lower canes. Some raspberry fields will require pre-bloom insecticides on a case by case basis. Watch blossom clusters for clipper weevil and raspberry fruit worm activity. Do not spray insecticides during raspberry bloom. 

Blueberries: Continue to apply fungicides for mummy berry and phomopsis, but remember these pre-harvest intervals: 

• Bravo: 54 days                           
• Topas: 60 days                          
• Funginex: 60 days                          
• Allegro: 30 days 

For blocks or varieties with a history of problems, Pristine, Cabrio and Switch can be used now for control of anthracnose.  Pristine and Cabrio will also control phomopsis. Spray if you have had history of problems with these pests. 

Use pheromone traps to monitor for cranberry fruitworm and cherry fruitworm. Be ready to apply an insecticide after bloom, based on peak trap catch. By using these IPM techniques you can reduce the number of insecticides required AND improve control. See Control of Cranberry and Cherry Fruitworm in Highbush Blueberries on the OMAFRA website: http://www.omafra.gov.on.ca/english/crops/hort/news/hortmatt/2005/08hrt05a5.htm . 

Preventing spray injury on berry crops: 

Stressful environmental conditions can make plants more susceptible to “spray burn” or phytotoxicity from sprays. Here is a list of reminders that can help you reduce the risk of spray burn on berry crops. 

•         Avoid spraying in hot conditions (ie. over 26°C) or in very humid, poor drying conditions.  

•         Avoid spraying immediately after a hard frost. Wait a day or two for plants to recover and rebuild damaged cuticles. 

•         Avoid adding surfactants unless required by the label. 

•         If spraying micronutrients or foliar fertilizer, be especially careful of surfactants, products containing surfactants, and tank mixes.   

•         Do not apply boron, chelated micronutrients or water-soluble fertilizers with products packaged as solupaks. 

•         Avoid spraying captan, Maestro, Bravo for 2 weeks following oil application (including Agri-mek+oil) 

•         On strawberries: do not use Furadan on Annapolis,Cavendish, other varieties may also be sensitive. 

•          On strawberries: Do not apply Sinbar within 2 weeks of Poast Ulta +Merge or Venture L: the surfactants in the grass herbicides can increase uptake of Sinbar. Low soil organic matter, susceptible varieties, low water volumes and higher application rates can all increase the risk of Sinbar damage on strawberries.  Use at least 120 L water/acre, and use the lowest rates on sandy soil and sensitive varieties like Mira, Kent, Annapolis and others.  

•          Ideally, use a dedicated sprayer for herbicides. Even if the sprayer has been "rinsed out" with water, the addition of surfactants or liquid fertilizers to the next tank load may cause inadvertent loosening of previous residues. See “Avoid Getting Burned By Herbicide Residues” http://www.omafra.gov.on.ca/english/crops/field/news/croppest/2005/06cpo05a3.htm

The Ontario Highbush Blueberry Growers are planning a meeting Friday May 29, 2009, at Barrie Hill Farms. Guest speaker will be Mark Longstroth, from Michigan State University Extension. The meeting begins with a farm tour at 2 p.m. For information please contact Celia Klassen at klassenb@xplornet.com