In the past couple of weeks the weather has fluctuated from mild, seasonal temperatures with about an inch of rain, to the more recent cold, wet snap. Seasonable day time highs, during the sunny period, and consistently cool night time lows along with the accumulated rainfall overall have been adequate for plant growth. The slow pace of spring development has caused extended, overlapping bloom periods, azaleas and rhododendrons are particularly spectacular right now. Lawns have greened up and mowing season is in full swing. On average 213 growing degree days have been added so far this season, and the soil temperatures have reached an average of 61 degrees. Of course as the growing season continues so do the potential pest problems. In addition to continued activity from wintermoth caterpillar, fall cankerworm, azalea sawfly, forest tent caterpillar, pine sawfly, spidermites, leaf beetles, lacebug and HWA a few more pests have arrived on the scene.
The fluctuating temperatures and variable rainfall amounts have not hindered pest populations entirely. Now that daytime temperatures are seasonable and overnight lows are consistently above freezing, insect activity is also somewhat consistent.
- Azalea whitefly is now active and sighted closer to the east coast more often than inland and western regions. Honeydew, sooty mold and stunted growth may be signs of a whitefly problem. They produce generations which overlap making them hard to control, so consult with your arborist if you have any concerns.
- Many species of aphids are coming into their free feeding life cycle stage. Populations will build on the underside of leaf surfaces, with the possibility of natural predators mixed in. Discuss the necessity for treatment with your arborist.
- Cottony camelia scale or cottony taxus scale are now active, Taxus and Ilex species are common hosts. White, cottony appearing egg sacks will be present on the underside of foliage, and if the stems already have sooty mold that may be an indicator of last season’s population.
- Roseslug sawfly caterpillars are actively feeding, the common name refers to the slug like appearance of the larvae. Their host can also be inferred from the name, these caterpillars feed on leaves of rose plants using scraping mouthparts to remove patches on upper leaf surfaces. If populations are large, damage can be extensive, causing almost complete defoliation. If you suspect a problem, call your arborist to discuss your options.
Treatments need to occur at the times when they will be most effective, of course, sometimes the weather prohibits the ability or effectiveness of products. Your arborist and plant healthcare technician will schedule applications and monitoring as suited to your landscape’s needs, expected leaf out, insect life cycles and ideal weather. Because weather patterns are not one hundred percent predictable and pest problems are not an exact science, plant healthcare has to be flexible and adaptive, be assured they are doing their very best to get and maintain the optimal results for your landscape.