Observation is your number one tool in maintaining and enjoying healthy plants. Be on the lookout for the usual issues you see in your location, learn when it is time to look for and see first infestations of disease or insects where you live.
You may find resources in our Useful Links page, or from your local co-operative extension office.
Also keep your eyes open for new surprises. Here are a few things I’ve noticed at home this spring:
- My apricot and peach trees are not coming out of dormancy with vigor (probably a mixture of leaf and bud blights caused by late hard freeze this spring followed by fungal disease infections).
- Thatching ants are chewing on my rhubarb, where the leaf blade meets the stems, which can result in death of my younger plants.
- Blueberry leaves are more purple than green, indicating the root systems are not picking up nutrients properly. If this was mid-summer I would be concerned about pH, while the soil is cold and wet in the spring however the plant roots have a more difficult time picking up nutrients and the foliage often will be off color. If I don’t see improvement a little liquid fertilizer for acid loving plants will perk up my blueberries.
- All of my pears, European and Asian, set fruit well this year, I may need to thin. One of my Asian pears is going to have to be removed, it is nearly dead now from pseudomonas infection. I will replace it with a less susceptible variety (learning opportunity).
Important things to do this month
Mow. Keep grass short and weeds under control. Avoid hand digging of weeds under blueberries, their roots are shallow and easily damaged. Sheet mulching is an effective way to reduce weeds without damaging shallow roots. Put a 1-2” layer of compost or organic material on the surface, a layer of newspaper (several sheets) or cardboard, and then wood chips or bark
Avoid using broadcast weed and feed lawn products within the root zone area of your fruit trees, which can be harmed by the herbicides when they soak into the ground. The typical spread of an established trees root system is 3-5 times the width of the canopy, with the most active part starting at about the edge of the leaf canopy and extending outward about ½ the width of the tree. Spray drift from glyphosate (in Roundup and other products) can cause dieback, stress, or death when it lands on and penetrates into thin bark. It can also cause bark lesions in stone fruits if absorbed through the roots. Symptoms may not be present until the following year. The pre-emergent herbicide dichlorbenil (in Casoron) leads to stunted yellow leaves and death if over-applied or used repeatedly.
Thin fruit of peaches, nectarines, apricots, plums, gooseberries, apples and pears before the June drop. Fruiting plants will naturally shed surplus fruit to maintain a healthy energy balance in the tree. If you remove a bit more fruit than the plant would normally shed, the remaining fruit will tend to be larger. Also, you can reduce the tendency for a tree to have alternate bearing years by evening out the crop each year. Thinning should be completed before the tree would naturally drop its fruit, or before the end of June in the Pacific Northwest.
Install bird netting to keep birds out of your favorite fruits if they were a problem for you last year. The small mesh black netting is useful over strawberries, blueberries, and other small sized plants or bushes. For larger fruit trees or grapes we offer 17’ wide medium weight commercial netting (#T432) and 22′ wide heavy duty commercial netting (#T431) that will allow you to cover a tree or trellis with one piece.
Spray apples against bitter pit in mid-June if you saw symptoms last year in your fruit. Bitter pit symptoms are circular or slightly irregular depressed spots on the fruit surface, with brownish or streaked off-color areas under the depression in the meat of the fruit. Pits are usually more numerous on the blossom end of the fruit, and can show up before or after harvest. Bitter pit is a physiological disorder, not a disease, caused by in-sufficient calcium available during fruit development. Hot, dry weather in July and August, irregular irrigation, heavy dormant season pruning, over thinning of fruit, and excessive nitrogen fertilizer can all contribute to an in-balance of calcium in the tree, resulting in bitter pit symptoms. Calcium chloride or calcium nitrate sprays can be used to correct an imbalance, follow the instructions on the package.