This is the first in a series we are doing on the invasive pest species that torment the Sacramento area. All of these pests are not native to Sacramento and are a nuisance either causing damage to plants (like the Spotted Wing Drosophila we are covering today), harming people or other animals, or competing for resources from native species which can have negative consequences for the overall ecosystem of the area.

Spring is upon us in Sacramento and this brings the glorious pink blossoms of the cherry tree. Sacramento is so full of cherry trees that it is affectionately refereed to by many Japanese visitors as Sakuramento, combining the Japanese word Sakura (cherry blossom) and Sacramento. Our beautiful cherry trees have recently come under attack however, as the Spotted Wing Drosophila (SWD) has recently begun terrorizing Sacramento since 2008 when it was accidentally brought over from Asia.

These tiny fruit flies may not seem too troubling and they pose no direct threat to people, but when they lay their eggs in the fruit of a cherry tree they can ruin all of the harvest before anyone has a chance to pick them. After SWD eggs hatch the cherries get full of tiny white maggots that destroy the fruit and make it undesirable for human consumption. If you have a cherry tree in your yard this is definitely a pest to watch for, and if you are a Sacramento cherry farmer I’m sure this is a pest you already know all too well.

Here are the top seven ways to prevent Spotted Wing Drosophila from wrecking your cherry harvest:

  1. Excellent sanitation: Fruit should be harvested frequently and cleanly. Remove culled fruit from the field and either freeze it, “bake it” in clear plastic bags placed in the sun, or dispose of it off-site. This will kill larvae, remove them from your garden, and prevent them from emerging as adults.
  2. Canopy and water management: Prune plants to maintain an open canopy. This may make plantings less attractive to SWD and will improve spray coverage. Leaking trickle irrigation lines should be repaired, and overhead irrigation should be minimized. Allow the ground and mulch surface to dry before irrigating.
  3. Insecticide treatments: Before applying a pesticide, always read and follow all directions on the pesticide’s label. Be sure to look for and follow any restrictions on when you may harvest your fruit after applying an insecticide. Pre-emptive insecticide treatment beginning when susceptible fruit first begins to color and continuing to harvest, according to the label instructions, will help protect fruit from infestation. Treatments should be repeated in the event of rain. Choose the most effective insecticides, when known. Alternating the use of insecticides with different active ingredients will reduce the chance of insecticide resistance developing in SWD. If fruit infestations occur, practice complete sanitation, as described in 1 above, and immediately apply an insecticide spray. See table below for a list of insecticide products. For insecticides that work primarily through ingestion (e.g. spinosad, acetamiprid), adding a small amount of cane sugar (2 tsp/gallon water) to the spray tank mix can improve results. Never apply insecticides during bloom or when bees are active.
  4. Monitoring for SWD with baited traps: For more information on trap construction and baiting, see Traps should be hung in midcanopy or on the north side of the row. Check the traps daily or weekly. Traps using currently suggested baits are moderately effective in giving early warning of SWD presence in a planting and can indicate relative numbers of SWD in an area, such as after treatment with insecticide. Also consult your local extension office or SWD web sites for reports on SWD monitoring in your area.
  5. Fruit sampling: Check at least 25 fruit for infestation between sprays to determine spray efficacy. Fruit can be analyzed for larvae by placing about 25 fruit randomly gathered from the garden into a Ziploc bag. Add a saltwater solution (1-2 tsp salt per cup of water) and leave for 15 minutes for the larvae to emerge from the fruit. Look for small, white larvae floating in the salt water.
  6. Cooling berries immediately: Chilling berries immediately after harvest to 34° to 36° F will slow or stop the development of larvae and eggs in the fruit.
  7. Use of Insect Exclusion Netting: For small plantings, use of insect exclusion netting (1 mm (1/32 inch) mesh) may protect the planting from infestation.

If you believe that you may have Spotted Wing Drosophila or any other pests that are bothering you contact Fast Action Pest Control for a free inspection to get a quick response and fast results.