Weekly Pest Alerts for May thru Sept 2018

Douglas County Extension Horticulture, Weekly Pest Alert Comments - 2018 by Steve Renquist
Questions? Email steve.renquist@oregonstate.edu or call 541-236-3047

Weekly Pest Alerts

June 26

Codling moth pressure in unsprayed orchards is very high now. In the sprayed orchards from one week ago there are no new moths in the traps. If you have not sprayed for several weeks, you should make a next spray sometime during this week. The mild temperatures make it optimum breeding time for SWD, codling moth and other pests. I encourage you to keep picking your berry crops as soon as they color up since the SWD pressure is great, especially in unsprayed berry plantings. I have noticed in my side by side blueberry and raspberry plantings that the raspberries are having more pest pressure.

We are reaching the time of this growing season to expect pressure from the filbertworm with Hazelnuts. There is a nice crop on the trees and the weather is very mild so within the next week to ten days put your first control spray on. Homeowners can use Spinosad, while most commercial growers in our area prefer Asana.

Vineyard crops look very nice at this time. If you are a homeowner with table grapes your grapes are often hybrids which are quite resistant to powdery mildew. You may only need one or two mildew sprays all season even under heavy mildew conditions like this spring. Commercial vinifera vineyards are into their 7-10 spray program. Make sure to rotate your fungicides between different frac groups and remember there is resistance to group 7 and 11 fungicides in our area. If possible keep some of the fungicides like sulfur which doesn’t experience resistance in the rotation.

June 18

No codling moth caught in the traps this week. No need to spray if you sprayed within the past ten days. Pressure still high from the SWD for blueberries and cherries. Keep harvesting ahead of the pest pressure. If you have been getting soft fruit when you harvest, you may need to make one more Spinosad spray and wait a week to begin your harvest again.  This should knock the flies back and allow you a week or ten day harvest period without heavy pest pressure.  

Grapes are looking very nice this year. No sign of powdery mildew on vines that were sprayed one time a few weeks ago. Sulfur is a good choice for grapevines to prevent the mildew.

June 11

The codling moth traps did catch two moths this week, so make another application of Cyd-X or Spinosad. Just keep alternating products when you have at least two moths in a trap for the week.  SWD pressure still pretty high. Keep checking your vinegar traps and know that blueberries and cherries are their main target crops at this time.

I have noticed a lot of apple scab on small apples this year despite having made fungicide sprays. It is a good idea to just drop those fruit that have much scab. They will not be much good except if you make a lot of cider or apple sauce.

June 4 

No catches in the Codling moth traps. Keep monitoring. The SWD have really gotten heavy in the vinegar traps in cherry trees. Monitor closely to make sure you make a spray of Spinosad when the cherries start to color up.

May 28

The SWD catches in the cherry orchards continue to be very large with counts over 50 again. Anyone with cherry crops that are starting to color need to make their first control spray this week if they did not spray last week. If you sprayed a week ago and your cherry crop is not ripening quickly because of the cool weather this week, you may need to make another spray next week.

Codling moth traps had 3-4 moths in them this week at locations where no spray was made last week. No codling moth catches were made this week in orchards that were sprayed last week. The most critical spray for codling moth control is often the first one that usually falls in late May for the Umpqua Valley. This spray will work to keep a lid on the overall codling moth population as the summer progresses. It is also important to keep monitoring your traps all summer into September and when you catch two moths in one week, make another spray. Remember to clean out your traps each time you record the weekly catch numbers. Always rotate your chemical sprays after each application to minimize resistance buildup.

I noticed pretty heavy pressure from flea beetles on new seedlings in my vegetable garden again this year following the mowing and shredding of the cover crop. Cover crops are great for the soil but during the decomposition phase in the new garden, the insects that aid organic matter decomposition can start chewing on new seedlings. If you have problems with new seedlings being eaten, one application of Spinosad will usually be all that is needed to give them time to grow past the pests.

If you have grapevines that are not hybrids or concords with powdery mildew resistance, it is a good time to make your first fungicide spray. There are a number of fungicides that work well for homeowners but the easiest to find is sulfur. Sulfur is also good for homeowners since you can use it several times in a row without worrying about resistance developing.   

May 21

The cherry crop has started to color with the warmer weather. This has made a big jump in the SWD catches in the vinegar traps this week. Several of traps had catches with over 50 with both male and female SWD present. It looks like a good time to make a control spray if you have any cherries beginning to color. Spinosad or Malathion are chemical choices for homeowners to control SWD. Don’t wait too long to spray with potential pressure this high. Codling moth traps also had 2-3 moths this week. That is enough to hit the spray threshold so now is a good time to make that spray too. Spinosad, Cyd-X, and Surround, are organic options, while Malathion and Sevin will work for conventional controls. If your traps had one or no catches, you can wait another week and monitor. Your fruit thinning for apple, pear, peach, and plum should be finished by the end of May to ensure a good bloom and fruit set for next year. Don’t wait too long.

May 14

I found no new codling moth in my traps this week so I did not have to make a spray. The vinegard traps for Spotted Wing Drosophila were also not catching much. It is still pretty early for any of the fruit crops to be attracting SWD. As the cherry, and berry crops ripen the SWD will come in fast with big numbers. I did notice some apple scab on leaves of apples and on ornamental crab apple. One more protective spray should be made if we get rain forecast within the next week.

May 7

A mild winter pushed all the fruit trees to bloom about 2-3 weeks earlier than the last couple of years. The mild winter was followed by a cool spring slowing crop progress a little for both berry crops and tree fruit. With average to slightly above average heat unit accumulation year to date, insect emergence has been right on the twenty year averages. One of my codling moth traps did pick up 4 moths over the past week and a second trap caught 6 moths. These catches are at or over the needed threshold of 5, so clean out the traps and make your first codling moth sprays for apples, pears, and plums within the next 10 days. As we go forward
always remember to clean out the traps so your new weekly monitoring will be accurate. As we move into the new week any trap with 2 or more moth catches should be followed with another spray. For organic growers when we start our codling moth spray program use Spinosad, Cyd-X, Surround, horticultural oil, or superior oil. If you are not an organic grower you can use non organic products like sevin or malathion. Don’t use the oil products on your fruit trees if the temperature is over 85 degrees at any time during the day or within two days following the spray. This year has had a couple hot days in early May so make sure none are forecast when you use any oil based products.

We are also monitoring for apple or pear scab presently. I noticed on several Gala apple trees new scab infection on leaves. It is important to put fungicides on your fruit trees, grapevines and berry crops to protect them from powdery mildew, scab, or other fungal diseases. You should always put on a fungicide spray to prevent these diseases so get the spray on now if the weather forecast looks dry for a day or two. Organic growers are restricted to using dusting sulfur or wettable sulfur. Conventional growers can use captan, or immunox. Buy 2 or more insecticide products, and alternate their use as I advise the timing in the weeks ahead to prevent resistance by insects. Sulfur is a product that has not experienced disease resistance issues.

Remember to get vinegar traps out in your orchard and berry crops to monitor for Spotted Wing Drosophila. These small vinegar flies have been laying eggs in berry, cherry, and peach crops the past few seasons and will need to be controlled as your fruit crop gets near full size. I will advise you when to apply controls, however it is important to know if they are around your fruit crops presently.

Researchers have been trapping Brown Marmorated Stink Bugs (BMSB) around much of western Oregon during the past year. These insects can cause a major amount of damage to fruit and vegetable crops so look up what they look like and keep alert. These pests especially like English holly and Tree of Heaven (Ailanthus altissima) to gather and live in. Researchers have been getting good control of these pests by treating the  ornamental host plants with systemic insecticides. I have put out some traps in several areas of Garden Valley to follow the population buildup of the BMSB.With the slightly early tree fruit growing season you should plan to start fruit thinning about 20-30 days after petal fall. We saw petal fall from most tree fruit crops in mid to late April. Apples, pears, peaches, and plums often set way to much fruit. Thinning fruit will improve size and quality, plus keep your tree branches from breaking. When you are thinning off fruit look for damaged fruit and remove them. Pears, peaches, and plums bloomed early this year so thinning should commence now. Wait on apples until May 12.