As we approach the end of bloom, growers should consider the need for any post-bloom applications. The main pest targets for these applications are mainly Sparganothis fruitworm and spotted fireworm.
Sparganothis fruitworm (SPARG)
Pheromone trap catches for SPARG indicate that we passed peak flight. Although SPARG populations have been on a decline in recent years, some farms and farm sites in New Jersey have a history of high SPARG infestation. If your farm is one of these, you should manage this pest as soon as bees are removed.
The timing for this 1st post-pollination spray is at 2 weeks after peak pheromone trap catches and this year should be next week (July 1-8). Insect Growth Regulators (IGRs) (e.g. Intrepid and Confirm) are effective against SPARG and can be used during bloom. Alternatively, if you have used IGRs intensively (e.g. last year and this year as a pre-bloom spray), and would like to rotate with other chemistries, you may want to use Delegate, Altacor, or the broad-spectrum insecticides Diazinon or Lorsban. Broad-spectrum insecticides are also a choice if you have high blunt-nosed leafhopper populations because Intrepid, Delegate, and Altacor will have no effect against this insect. If you are an Ocean Spray (OS) grower please check restrictions on the use of these insecticides. Lorsban in particular can’t be used by OS growers after bloom due to MRLs for exporting cranberries. If you are an OS grower and want to use a post-bloom application to control SPARG then Delegate, Altacor, or Diazinon would be your options.
Spotted fireworm (SFW)
SFW is one of the most important pests in New Jersey. Male SFW moth catches typically peak in the second through third week in June.
Although trap catches give an indication of population size, these numbers not always correlate with numbers of egg masses. This insect becomes a problem in “weedy” beds because female moths lay their eggs predominantly on weeds. Thus, growers need to monitor for the presence of SFW egg masses on weeds (broadleaf species and grasses). Keeping beds clean from weeds will keep this insect under control. Egg masses should be hatching by now. SFW larvae from this generation feed on foliage as well as fruit. Damage to foliage causes a characteristic browning of uprights. Most effective control of SFW is achieved when larvae are in early stages of development, and not tightly enclosed in leaves or entered the berries. There is no economic threshold based on number of egg masses.
If SFW populations are high, you may apply the IGRs Intrepid or Confirm during bloom to target the early-instar SFW larvae. IGRs are safe to bees. This application will also control other lepidopteran pests such as SPARG (see above). An additional benefit of using IGRs is that they are soft to the pest’s natural enemies. SFW eggs are heavily parasitized by Trichogramma spp. Parasitized eggs are black compared to the yellow-orange color of unparasitized eggs. Post-bloom insecticide options to control this insect are the same as those listed for SPARG.