Orchard notes week of June 13

By Terence Bradshaw

After the past week of rain I expect any remaining apple scab ascospores to have been released. Maintain fungicide coverage through the next week or so, and check orchards methodically for scab lesions to determine if you’re really done managing the disease for 2016. Summer diseases, particularly sooty blotch and fly speck however will start becoming a concern next week or so when more leaf wetting hours accumulate, but for now, if your coverage was good during scab season, you’ve probably got a week off from managing fungal diseases.

Fire blight however is appearing in orchards across the state. Most growers are reporting sporadic strikes on trees that received no streptomycin; I haven’t heard of anyone with a major outbreak but please let me know if our orchard is venturing into that level of disease. Dry, sunny weather Wednesday – Friday will be good timing for cutting out strikes. Prune well below the site of infection, sterilize between cuts with alcohol or 10:1 bleach solution if you can, and for now just drop the cut tissue on the orchard floor until it can dry out, pick it up later. Time and effort this week should be spent on removing infected tissue from the tree.

Insect activity is high across the state. Plum curculio is winding down, orchards with recent coverage of a suitable material are probably okay for this pest. I am seeing higher than expected catches of codling moth in many orchards monitored by Eric Boire from CPS. For those with >5 moths per week trapped in the past couple of weeks, a second lepidopteran-specific spray (everyone sprayed for CM last week, right) is due.

The window is closing to apply nitrogen fertilizers for 2016. If you have a light crop or fire blight (or both), no more nitrogen should be applied this season to prevent excess vegetative growth which is susceptible to fire blight and some insect pests.

If you’re not cutting fire blight this week then focus on groundcover management. Small amounts of weed cover in the tree rows at this time of year turns into a real headache in late summer-early fall.