The Plant Lady: Garden nuisances can be dealt with and your plants will thank you
With spring blooms also come garden pests and diseases. Many diseases/pests lay dormant waiting for the perfect conditions – water, warmth and increased sunlight – to then emerge and feast on your plants. But do not fret. Most of these nuisances are not as problematic as they may seem, and a few control/mitigation strategies can help your garden thrive. Below are the most common early spring concerns of most gardeners.
Peach Leaf Curl
Along with peaches, the fungus (Taphrina deformans) can attack nectarines and even almonds. The tell-tale symptoms are red, puckered, twisted leaves. Spores lay dormant on the bark, and when conditions are ideal they burst open to grow and distort leaves. Once a tree has symptoms, assume it is “infected” with spores. In spring –
when symptoms arise – there is no control.
If leaves fall off, throw away in the garbage. If a good portion of the tree defoliates, apply nitrogen to replenish the nitrogen used to make a secondary flush of foliage. Issues arise when a tree is not treated, and in subsequent years the infections can result in limb dieback and tree decline. Prevention and treatment occurs after leaf drop in fall and right up until bud break, with applications of liquid copper. Ideally spray once in November, December and January. Of course during many wet years it is difficult to get even one spray in.
Spring weather is usually a determining factor on severity of outbreak – the wetter the spring the worse it can be. Fruit can be affected as well. Some fruit will show scarring on the skin, and if the tree is suffering a severe attack it may not fruit at all.
If your other fruit tree species have twisted and curling leaves, note that it is not peach leaf curl but most likely aphids.
Aphids
The poster child for spring garden pests, aphids are a phloem sucker meaning – they pierce into the sugar transport of the plant and draw out sugars. A large, prolonged infestation can cause injury to a plant, but usually the infestation looks worse than it is.
Aphids emerge from winter as eggs, and will then feast on new spring growth. They can remain active year-round, most do not need a mate to reproduce and are born fully mature. Almost always with time and increase in temperatures they will disperse – so just be patient.
Zoom in close to your plant, and notice what is there along with the aphids. Ladybugs, syrphid flies and lacewings are just some of the natural predators that rely on aphids for food. If you see swollen beige bodies then you have parasitized aphids. Small parasitic wasps use aphids as a host for their offspring, which in return kills the aphids.
If your plant is suffering and/or you do not see any natural predators around, then a simple blast with a hose is an excellent control. Spraying a soap spray or neem oil is also a good recommendation. And remember to control ants if you notice them as they “farm” and protect the aphids. The goal is not eradication, but maintaining a manageable amount – beneficials and hosts need them for a good ecosystem.
Powdery mildew
There are many species of this foliar fungus, but you need to be an expert with a dissecting scope to differentiate. This fungus is very prevalent on spring roses, but can grow anytime during the year, including on many summer vegetables.
Powdery mildew is quite distinct in that it looks like a coating of white powder on your leaves. Almost always it will dissipate on roses with heat and sunlight. However, if new growth on plants continues to be affected, then mitigation controls can be taken. Neem oil and sulfur spray/dust are the safest controls. A few sprays may need to be done, and remember it won’t remove the existing powdery mildew but prevents the spores from adhering to new leaves. Powdery mildew will overwinter on live plant material – including weeds – so weed control is key for prevention.
Leaf-Footed Bug
A few years ago this bug would not have made it onto any of my pest concern lists. However, the last several years has seen an increase in the concerns and questions I get from gardeners.
There are several species in California, but in general the adults are easy to identify due to their namesake- swollen, flattened portions of their legs. The immature stages are redder and often have black spots, but differ with species.
They overwinter as adults in tall growth, sheds and pretty much any undisturbed area. In spring they will lay their eggs on leaves, and the adults will pierce into fruit and plants causing the leaves/fruit to distort and discolor.
Control is tough – when you see them, knock them off. Generally, they only cause problems when numbers are high, but it is a good idea for future outbreaks to rid your garden of any you see. It is a manual effort.
The University of California has an excellent online source for all garden pests at http://ipm.ucanr.edu/PMG/menu.homegarden.html as well as my YouTube page https://www.youtube.com/user/MarleneThePlantLady
This story was originally published April 22, 2020 at 4:00 AM.