Spider mites are common, tiny garden pests, related to spiders and ticks. Usually microscopic, mites can be found in almost any habitat, including the human body. We refer to some mites based on where they are found: cheese mites, dust mites, eyelash mites.
The term “spider mite” is often used to refer to mites that attack plants. For instance in Oregon, spruce mite is a common pest of spruce and a few other trees. The two-spotted spider mite is a spider mite that feeds on many types of plants. The following information pertains specifically to two-spotted spider mite, and may also be true for other plant-feeding mites.
Spider mites thrive in hot, dry weather and cause damage to many types of ornamental and vegetable plants. In this article you will find information about:
Spider mites are a common and frustrating pest for cucumber growers. These tiny pests can quickly get out of control and devastate cucumber crops if left unchecked. In this article, we’ll look at what spider mites are, the damage they cause, and most importantly, how to prevent and control infestations on cucumber plants.
What are Spider Mites?
Spider mites belong to the Tetranychidae family and there are hundreds of species. The two most common mites that affect cucumbers are the two-spotted spider mite and the carmine spider mite. Adults measure only 1/50 to 1/20 inch long and vary in color from red and brown to yellowish-green.
Spider mites have needle-like mouth parts with which they pierce plant cells and suck out the contents. This damages the plant tissue and reduces photosynthesis. Spider mite feeding removes chlorophyll and other cell materials, causing small spots or stipplings on leaves. Webbing on the undersides of leaves is another clear sign of their presence.
Why are They a Problem on Cucumbers?
Cucumbers are very susceptible to mite damage for a few key reasons:
-
Cucumbers have large leaves which provide ample feeding sites for mites.
-
Cucumber varieties lack genetic resistance to spider mites.
-
Cucumbers are often grown in hot, dry conditions which spider mites thrive in.
-
Close plant spacing creates a humid environment inside cucumber rows, which spider mites prefer.
-
Broad spectrum insecticide use kills off natural predators allowing mites to multiply rapidly.
How to Identify Spider Mites on Cucumber Plants
Catching infestations early is critical to controlling mites. Here’s what to look for:
-
Tiny yellow, white, or brown spots on upper leaf surfaces, causing a stippled appearance
-
Webbing on underside of leaves
-
Leaves turning yellowish or bronze
-
Moving dots visible on undersides of leaves
-
Speckling and scarring on cucumber fruit later in infestations
Pay closest attention to the undersides of older leaves near the center of the plant. Use a hand lens to check for the presence of mites, webs, and eggs. also shake leaves over a white sheet of paper to dislodge mites for easier viewing.
Preventing Spider Mites in Cucumber Crops
Prevention is always the first line of defense against pests. Here are tips for preventing mite infestations on cucumbers:
-
Select resistant varieties when possible. Some cucumber varieties have moderate mite resistance.
-
Water plants regularly and avoid moisture stress. Drought stressed plants are more susceptible.
-
Control weeds within and around the crop. Many weeds harbor mites.
-
Use reflective mulches like aluminum foil fabric to repel mites.
-
Use row covers to physically exclude mites until flowering.
-
Avoid excess nitrogen fertilization which favors mite reproduction.
-
Monitor plants frequently and treat hot spots early before they spread.
-
Use selective insecticides to conserve natural mite predators.
How to Control Spider Mites on Cucumbers
If preventative measures fail and mites gain a foothold, taking quick action is essential to avoid major crop losses. Here are effective control options:
Insecticidal Soaps
Insecticidal soaps penetrate the mite’s protective outer layer and cause dehydration. Spray plants thoroughly covering undersides of all leaves for best results. Applications may need to be repeated every 3-5 days for 2 weeks.
Horticultural Oils
These oils coat mites and eggs and smother them. Use a 1-2% solution and repeat applications may be needed. Be cautious when temperatures exceed 90°F to avoid plant damage.
Predatory Mites
Mite predators like Phytoseiulus persimilis can provide longer term control when released early in infestations. They are best suited to greenhouse settings. Repeat releases are often necessary.
Miticides
Products like abamectin and bifenazate are effective but must contact mites to work. Rotate modes of action to prevent resistance. Carefully follow label directions on precautions and application intervals.
Water Sprays
Strong water streams can wash off mites and make conditions less favorable for them. Spray the undersides of leaves where mites congregate. Repeat treatments may be needed.
Row Covers
Installing row covers after infestation provides a physical barrier preventing mites from recolonizing. Use until flowering then remove to allow pollination.
Crop Destruction
For severe, uncontrolled infestations, removing and destroying crops may be necessary to prevent mites from spreading further.
The key with any control method is taking action early before mites become well established. Frequent scouting and monitoring, starting just after seedling emergence, is critical for staying ahead of problems. If preventative measures fall short, implement controls at the very first signs of mites.
Impacts of Spider Mites on Cucumber Yields
Unchecked spider mite infestations can significantly reduce cucumber yields. Some impacts include:
-
Reduced photosynthesis from stippling and chlorosis of leaves
-
Premature leaf drop and loss of foliage reduces plant vigor and capacity
-
Flowers and fruit buds may abort due to plant stress
-
Poor fruit fill and undersized cucumbers
-
Scarring, bronzing and flecking of fruit making it unmarketable
Losses over 50% can occur in severe infestations. Keeping mite populations in check early on is essential for avoiding major yield impacts.
How to Prevent Mite Resistance to Pesticides
Overuse of certain miticides can cause mites to become resistant. This renders products ineffective and leaves fewer control options available. Here are tips to slow the development of resistance:
-
Limit use of high risk products like abamectin and bifenazate to when absolutely necessary
-
Alternate among chemical classes with different modes of action
-
Follow label limits on frequency of applications
-
Rotate miticides between seasons
-
Always use labeled rates. Reduced rates can increase resistance.
-
Monitor effectiveness and switch products if control failures occur
-
Employ non-chemical control methods like oils and soaps
-
Target applications only where needed instead of whole fields
Following resistance management practices will help maintain the efficacy of available miticides against spider mites.
Spider mites pose a serious threat to cucumber crops, especially under hot, dry conditions. Their rapid development allows populations to explode quickly. Good cultural practices and early intervention at the first signs of infestation are key to effective control on cucumbers. Insecticidal soaps, miticides, and natural predators provide options for keeping mites in check when prevention falls short. Catching problems early and exercising good resistance management will allow cucumber growers to enjoy bountiful, mite-free yields.
How to treat for spider mites
As with most pest problems, mites are easiest to control when caught early. It’s important for gardeners to check for spider mites when it’s hot and dry outside by looking for the above signs.
- Pinch off the affected plant part and destroy it.
- To get rid of the mites, hit the plants with a high-pressure jet of water (not good for very young or fragile plants).
- By watering from above or misting the plants, you can raise the humidity around the plant. (Note: wet leaves can contribute to plant disease).
- Remove and destroy affected plants, when practical.
- Keep your garden’s habitat varied to attract predatory mites and insects that can help get rid of two-spotted spider mites.
Conditions that allow spider mites to thrive
Spider mites thrive in hot, dry weather. For spider mites, the best conditions are temperatures in the upper 80s (F) and above, and humidity levels less than 200 percent. However, populations can build up any time humidity is lower than 90%. Every 5–7 days, a new generation of spider mites grows when these conditions last, especially when the nights are warm. Because mites are small and hard to see, and their populations grow quickly, it seems like a lot of them showed up all at once.
Drought-stressed plants are easily damaged by spider mites. When there is both drought stress and spider mites on crops, it is possible for the crops to lose 50% or more of their weight.
Pesticides often kill predatory insects and mites that would have kept the mites in check, which is thought to cause mite flare.
The use of certain broad-spectrum chemicals to get rid of other insect pests is another thing that leads to large spider mite populations. It is possible for these pesticides to cause mite flare, a condition in which mite populations rise, when they are used to get rid of other pests.
Pesticides often kill predatory insects and mites that would have kept the mites in check, which is thought to cause mite flare. It can also happen because some insecticides make spider mites reproduce faster than they would normally. Spider mites are not insects. Therefore, consider using “soft” pesticides that are of reduced risk in harming beneficial insects and mites.
Battling Spider Mites Organically in the Cucumber Patch
FAQ
How to control spider mites on vegetable plants?
Do spider mites eat cucumbers?
Can a plant heal from spider mites?
What is the best treatment for spider mites?
What plants do spider mites eat?
Spider mites will infest most plants that a home gardener or market grower might raise. Tomatoes, lettuce, peas, beans, cucumbers, zucchini, winter squash, strawberries, blackberries, and fruit trees are all targets. They will also attack houseplants if conditions are ripe.
Do spider mites eat leaves?
By treating and preventing a minor spider mite infestation affecting only a few leaves, the plant can recover to a healthier state. It’s easier to spot the damage spider mites inflict on leaves than to look for the nearly microscopic pests on the plants. Here’s what to look for. Spider mites feed by sucking out plant juice from the leaves.
How do I get rid of spider mites in my garden?
Drought-stressed plants are more likely to attract spider mites. Keeping your garden well watered and your soil fertile will go a long way toward helping to keep your plants strong and able to shrug off a few mites. Right plant, right place is the central pillar of Integrated Pest Management.
What are tiny red spider mites on house plants?
Tiny red ‘spiders’ on house plants and greenhouse crops are actually sap-sucking mites called red spider mites. There are many types of spider mite, but in the UK the red spider mite ( Tetranychus urticae) is the species most likely to be found on indoor and greenhouse-grown plants.