This One January Spray Stops Thousands of Garden Pests Before They Ever Hatch

We’ve all heard the old maxim “Let sleeping dogs lie” but this doesn’t hold up when it comes to bugs. There is no upside to leaving snoozing pests on your favorite plants. In fact, when insect pests pass the winter sleeping in your fruit trees, it’s considered the perfect opportunity to attack.

Aphids, scale insects, codling moths, caterpillars, and spider mites tend to pass the winter season in fruit trees, often as eggs. There, they patiently await spring, when they emerge to begin a long season of munching on your plants. It’s a common tree mistake to think you can banish these pests with pesticides in spring.

The truth is that it’s easier, safer, cheaper and more effective to use one spray on overwintering pests in January – and that’s dormant oil. Here’s why it works in January, and why it can help you in the garden now.

What Is Dormant Oil?

Dormant oils are horticultural oils – that is, plant-based or petroleum-based products that are meant to be applied during the period of the year when the plant is dormant, usually in winter and early spring. Organic neem oil is one of the best alternatives for fruit pest sprays, but copper and sulfur oils are also important for some fruit trees.

So why should you apply dormant oil? The purpose is to target pests that are found on plants in winter. Spraying with dormant oil in January helps control overwintering insects and insect eggs in your home fruit trees as well as woody ornamentals. One highly rated and reliable brand for gardeners is Bonide All Seasons Dormant Spray Oil from Amazon, which is highly effective on these fruit trees during the dormant season. Monterey and Sunspray are other highly rated brands for dormant oil products you can use on overwintering pests.

Risks of Overwintering Insects

Overwintering insects are born on your fruit trees. That gives them ample time and opportunity to damage them as they hatch out and feed on their bark, leaves, and fruits. This can weaken the tree, reduce its vigor and growth, and result in less (or lower quality) fruit.

Some pests also spread diseases to the trees. Other pests, including sap-eating aphids, compete with the tree for nutrients. Still others, like the codling moth, burrow deep into the fruit, making it inedible. Every single insect pest is ready, willing, and able to propagate their species quickly and effectively in spring.

The risk of overwintering insects is greater in some fruit trees than others. Apple, pear and peach trees are particularly at risk, as pests like aphids and mites can hide in their bark as well as their foliage. Insects like woolly apple aphids and European red mites are known to overwinter in the bark. Peach trees are at risk for plum curculio pests, known to damage the fruit.

1. Dormant Oil Is Easier

Spraying dormant oil on insects and their eggs in January is oh-so-much easier than trying the same trick with pesticides in summer. For one, the leaves have fallen from deciduous trees, giving you a clear shot at the areas of the tree where eggs and bugs might cluster.

The dormant oil suffocates the eggs and larvae. At the same time, it places a barrier of protection on the plant surfaces. This can smother adult pests like aphids, and slow down fungal spores from germinating.

2. Dormant Oil Is Safer

Most everybody is aware, these days, that chemical pesticides can cause as many problems as they solve, if not more. They may do a good job of taking out pests, but they also kill beneficial bugs like pollinators and beneficial insects which prey on pests.

Dormant sprays have virtually no downsides. Organic neem oil is the best choice, but even if you go for a dormant oil that is petroleum based, these oils have a low UR (unsulfonated residue), meaning that most of the toxic compounds have been removed. Because dormant oil is sprayed during the dormant period, fewer pollinators and beneficial insects are at risk.

3. Dormant Oil Is Cheaper

Dormant oil won’t break the bank, even if you go for organic neem oil. The cherry on the top is that you only use it in the dormant season. Spray neem oil in winter, and you are done for the year. Every smotherable insect on the tree is impacted. (Small caveat here: excessive oil can risk smothering the bark's ability to breathe. One thorough drenching application is the standard recommendation for dormancy.)

Pesticides are notoriously pricey, and repeat spraying is recommended. That’s because pests like aphids and spider mites reproduce so quickly in summer that they require constant management. While dormant sprays do involve an initial investment, using them leads to lower long-term costs by reducing the need for additional treatments. Chemical pesticides are more expensive in terms of ongoing expenses, since the applications must be repeated during the entire growing season.

4. Dormant Oil Is More Effective

If you apply dormant oil at the appropriate time and ensure coverage, it can reduce insect pests by up to 92 percent. To get this type of result, you must apply it when temperatures are above 40 degrees F (4°C) and there is no chance of frost. Wait for the wind to die down and the rain clouds to pass. Coverage is critical. To make your dormant oil application effective, ensure a thorough coverage of all surfaces of the plant, including leaves if present, the undersides of leaves, and all branches.

However, while dormant spray provides very effective short-term protection against pests and some diseases during the dormant season, it’s not a cast-iron guarantee for pest-free fruit trees throughout the growing season. Several applications may be necessary to keep your fruit trees healthy as buds open and new growth occurs.

Don’t Forget – Winter Spray Checklist

Obviously, these products are lethal to overwintering pests, but make sure you are using them correctly and safely (and thoroughly). Here are the main guidelines for proper dormant oil spray success in your backyard:

• Safety First: Wear gloves and eye protection when spraying, even with organic products like neem. Use protective gloves like Showa Atlas Winter Safety Gloves from Amazon. Avoid inhaling the mist and ensure pets and children stay clear of the area until the spray has dried.
• Get the Timing Right: Apply your dormant oils in late winter or early spring before any buds open or fresh green growth appears. This timing is very important to ensure you catch pests while they are immobile (and prevent harming new foliage).
• Watch the Thermometer: Only apply on dry, calm days when temperatures are consistently above 40°F (4°C) for at least 24 hours. Avoid spraying if frost is forecast, as the oil can crack the bark if it freezes before drying.
• Prioritize Bee Safety: To keep pollinators safe, only spray while trees are strictly dormant (no open blooms). Spraying very early morning or at dusk ensures that any early-emerging bees aren't active, and oil has time to dry before they land on a tree.
• Check for Sensitivity: Always read the label first. While great for apples and pears, certain trees (like blue spruce, Japanese maples, walnuts) can be sensitive to oils and may suffer foliage burn.
• Hydration is Key: Ensure your trees are well-hydrated before spraying. Never apply oil to a drought-stressed plant, as this can cause the tree to absorb the oil into its tissues, leading to damage.

Winter Bug Zapping Essentials

Are you ready to zap those overwintering nasties before they tuck into your fruit trees? Make sure you're covered and get the job done right first time, and you'll save money and time later. Here’s your ready-made kit for effective dormant oil applications.

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