April 19, 2022. Spring weather is definitely being fickle teasing us with some warm days then waking up to snow and very cold morning temperatures! Some apples varieties are at green bud tip to tight cluster now. Red maples & forsythia are blooming, crabapples, hawthorn, chokecherries, current and shrub roses are leafing out. You should be finishing up your pruning now. Prune on a dry day if possible to avoid spreading disease. It is a good time to divide some late summer & fall blooming perennials.
Aphid hatch has been seen at our sample sites, 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. 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 show the first green color. Some trees are already past this point but you can use a low concentration of horticultural oil (1-2%). Most spray oils are petroleum or mineral based, but vegetable, fish, and neem oils are also available.. Oils can burn tender new leaf tissue, so apply them carefully. Lighter, lower concentration oil sprays are less likely to burn leaves. 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, it is past the time to apply a dormant spray. Wait until plants are done blooming to apply a fungicide to prevent diseases such as sulfur or copper.
Soil temperatures are still cool and are averaging 40. It’s close to 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 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. For sprouting perennials, purchase weed-killing formulations with oil and acid combination. Repeat sprays until you exhaust root reserves and plants don’t resprout. Tillage can also be used to kill newly germinating annual weeds. Till on a warm, dry day so weeds dry out and die.