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April 11th Pest Alert


April 11, 2022. With the warm weather last week, buds are swelling and breaking, but the cold weather this week could do damage. Not much we can do but hope that if buds do get injured that they will push out new replacements at a warmer time.  Here is more information on the cold temperatures and bud hardiness.

Red maples are blooming.  Early crabapple and hawthorn varieties, chokecherries, current and shrub roses buds are swelling.  You still have plenty time to prune.  Prune on a dry day if possible to avoid spreading disease.   It is a good time to divide summer & fall blooming perennials.   Voles have been enjoying the winter –check for girdling on apples, junipers & prunus species.

 Aphid hatch has been seen at our sample sites, (see attached picture) so it’s time to apply a preventative oil plus pyrethrum spray on green ash and red twig dogwoods if you have had problems with leaf curl aphid in the past. Green ash trees buds have swelled but you could still wait until you see green leaf tip before spraying.  If you had problems with mites, blister mites, aphids, scale, or leaf rollers last year, you might want to consider applying an insect-preventative horticultural oil spray now, as tree and shrub buds begin to swell and show the first green color. Most spray oils are petroleum based, but mineral, fish, vegetable, neem oils are also available. Oils can burn tender new leaf tissue, so apply them carefully.  Use oils when temperatures are above 40 F, but below 80 F. Oils should dry completely before they are exposed to freezing temperatures. Apply oils several hours before night temperatures drop.

If you had disease problems last year, you can also apply disease-preventative sprays to trees and shrubs now. If bacterial diseases, such as Fireblight, were a problem last year, the least-toxic disease preventative spray is copper or Bordeaux mix. If fungal diseases caused spots on leaves last year, copper or Lime sulfur is the least-toxic disease-preventative option. Don’t mix oil sprays with lime sulfur or copper-containing  sprays, especially if the weather is humid and temperatures are greater than 65 F. These sprays can burn sensitive new leaves and emerging buds, especially when sprayed in combination. On apricots use Bordeaux mix before bud-break if apricot scab was a problem last year. Check cherry, plum, and apricot trees now for oozing and cracking. Copper is the best disease preventative spray if you have bark cracking or oozing on cherries, plums, or apricots.

Soil temperatures are still cool at 40°.  It’s almost time to mow lawns and apply the first fertilizer application. Compost is a good 1:1:1 N-P-K ratio fertilizer that also helps to suppress turf disease problems and build soil structure. This is also a good time to aerate, before dandelions bloom! It’s time to test garden soil and decide what soil amendments are needed. Apply amendments 2-3 weeks before you plan to plant.  Cool season vegetables prefer soil temperatures of 40-50 F, so you can start planting peas, carrots, beets, lettuce and spinach outdoors now, especially if you cover the soil with clear plastic to warm soils and encourage seed germination.

Annual weeds are germinating now. It is a good time to treat them with vinegar/oil sprays. White and cider vinegar can be used on tender succulent annuals; but newly sprouting perennial weeds, such as quack grass and knapweed are not affected by these low acetic acid concentrations of vinegar. Tillage can also be used to kill newly germinating annual weeds. Till on a warm, dry day so weeds dry out and die.

Moss seems to be a problem in many yards this spring. Soil compaction is one of the main reasons along with shade and daily watering practices. The best way to control moss is to aerate your lawn and fertilize with a moss killing formulation or a finished compost applied ½-1” deep.