The infamous parasitic mite Tetranychus urticae is known for its rapid reproduction and ability to form colonies in record short periods of time. Spider mites feed on plant juices by penetrating cells and extracting vital nutrients. This leads to the depletion of plants, causing them to lose energy and nutrients, ultimately slowing their growth and resulting in the formation of lower quality and less productive crops. For example, cucumbers not only become smaller but also bitter in taste. Furthermore, mites can transmit various viral and bacterial infections, further compromising the health of plants.
Signs of cucumber infestation by mites include the appearance of interveinal chlorosis, yellowing of leaves, and webbing formation. To detect the pest, it is recommended to use 10x magnification and carefully examine the underside of the leaf. Another method is to use a white paper: tap the leaf to dislodge mites, and you will see them start moving on the paper.
During hot and dry weather, the mite population can increase up to 70 times in a week! Intense infestation is characterized by a thick white layer of webbing on the plant. The lack of moisture in the greenhouse makes cucumbers more vulnerable to attacks because under dry conditions, nutrients are concentrated in the leaves, promoting mite reproduction and worsening the condition of plants already suffering from water deficiency.
Mite feeding can lead to leaf drop in just a week and cause direct damage to cucumber fruits, ultimately affecting the yield. When mites start attacking the fruits themselves, it results in the appearance of a rough, paper-like texture on the skin.
Methods of Treating Cucumbers for Spider Mites
The choice of method depends on the severity of the infestation. For a mild infestation, normalize watering: periodically water cucumbers thoroughly with a strong stream of water from a hose, spraying both the upper and lower sides of the leaves. This will prevent mites and their eggs from resettling on the plants.
You can then use a solution of alcohol: one cup of alcohol to four cups of water. Thoroughly treat the entire plant surface. Alcohol destroys spider mites by dehydrating them. It is recommended to test-spray one cucumber to see how this method works under your specific greenhouse or garden conditions.
Many gardeners use onion infusion or fresh rhubarb leaves to combat spider mites. These plants are disliked by the pests, so mites tend to avoid them.
To prepare an onion infusion, chop half a kilogram of onions, then blend them until you get a creamy paste. Add a hot pepper pod if desired. Transfer the paste to a jar, pour two cups of room temperature water, place it in a sunny spot for a day. Strain the solution through a fine sieve – dispose of the pulp under the cucumbers, while the liquid can be used for spraying cucumbers as a biopesticide.
Rhubarb leaves contain several chemical compounds, including toxic oxalic acid. To prepare a homemade rhubarb spray, chop large pieces of 3-4 leaves, boil four cups of water, add the leaves and simmer on low heat for 30 minutes. Let the infusion cool. Then mix a teaspoon of dishwashing liquid with two and a half cups of cold water, combine this with the cooled infusion, pour it all into a sprayer, and treat the plants.
Using neem oil on cucumbers can also help combat spider mites. This product, derived from the neem tree, contains azadirachtin – an active ingredient that inhibits feeding, molting, mating, and egg-laying cycles of insects and mites. Neem oil should destroy spider mite eggs on contact. To prepare the solution, mix a teaspoon of neem oil with half a teaspoon of liquid soap in two liters of room temperature water – mix well and treat the affected areas or the entire plant depending on the solution volume.
If alcohol, neem oil, onion, or rhubarb are unavailable, liquid soap alone can be used – it's better than nothing. Dilute 10 ml of liquid soap in a three-liter container of water, stir carefully, pour into a sprayer, and treat the cucumbers after thorough rinsing with water to eliminate mites. This will help prevent pest feeding.
There are various acaricides designed to protect cucurbit crops, including cucumbers, from spider mites. In case of serious infestation, consider different commercial chemical pesticides containing active ingredients such as malathion, bifenthrin, cyfluthrin, and kelthane for combating the pest. Also, pay attention to acaricides with abamectin – this substance has proven effective in combating persistent pests like spider mites on both upper and lower leaf surfaces.
Attention is required! Before purchasing and applying pesticides, carefully read the information on the label regarding the permissibility of use in greenhouses, open ground, and compliance with regulations!
