The Latest Technical Methods and Tutorial for Cucumber Pest and Disease Control

Cucumbers are widely cultivated throughout China and are now extensively grown in temperate and tropical regions. They are one of the main greenhouse products and a common vegetable on the dining table. During cucumber cultivation, pests and diseases mostly occur as mixed infections, so when controlling diseases, be sure to pay attention to the compounding of pesticides and the flexible adjustment of dosage at different stages of disease onset. Let us now take a look at cucumber pest and disease control techniques!

Cucumber Disease Control

Cucumber diseases are mainly cucumber downy mildew, cucumber powdery mildew, cucumber anthracnose, and cucumber gray mold. The main reason for the appearance of these diseases is that as the weather warms up and temperatures gradually rise, improper management creates a high-temperature, high-humidity environment. The cucumber disease control techniques are introduced as follows:

1. Downy Mildew

[Damage Characteristics] Downy mildew is more serious in low-lying areas with poor ventilation and excessive watering. It mainly damages leaves, and occasionally stems and pedicels. In the early stage of the disease, there are water-soaked angular lesions. The lesions do not perforate. When humidity is high, black mold may grow on the back of the lesions. In severe cases, because the lesions are numerous, expand quickly, and merge with each other, the leaves become scorched and die prematurely.

[Control Methods] Ecological control: Maintain good ventilation in the greenhouse and control the indoor temperature, keeping it at around 25 degrees during the day and around 15 degrees at night. Chemical control: When the disease occurs, spray with 50% Juncheng diluted 2000 times with water. In severely affected areas, repeat the spray once every 3-5 days.

2. Powdery Mildew

[Damage Characteristics] Powdery mildew damages all aboveground parts of the plant, but mainly affects leaves and vines. In the early stage, small nearly circular white powdery spots appear on both sides of the leaves, then expand into large white powdery areas with indistinct edges. In severe cases, the entire leaf is covered with white powder. In the later stage of the disease, the white mold spots turn gray as the mycelium matures, and the diseased leaves turn yellow and withered with small black spots.

[Control Methods] Field management: Try to use disease-resistant varieties, ensure light penetration, water reasonably, reduce air humidity, and apply sufficient organic fertilizer. Chemical control: In the early stage of the disease, spray with Tiannuo Keli Feng fungicidal type diluted 1000 times with water, once every 5-7 days, repeating 2-3 times.

3. Gray Mold

[Damage Characteristics] Gray mold not only harms cucumbers but also damages green peppers, eggplants, kidney beans, etc. Gray mold mainly harms cucumber leaves, fruits, and flowers. The gray mold pathogen invades from faded female flowers, grows a gray-brown mold layer, and then invades young cucumbers, causing top rot, softening, and shrinkage. On affected large cucumbers, the diseased part first turns yellow, until it rots and falls off.

[Control Methods] Field management: Use high ridge cultivation, reduce field humidity, water reasonably, water in the evening, and ventilate properly to remove moisture and promote healthy growth. Chemical control: In the early stage of the disease, spray with 50% Sumilex wettable powder 1500-2000 times or 50% Duomeiling wettable powder 800-1000 times.

4. Anthracnose

[Damage Characteristics] Anthracnose mainly harms stems and leaves. Initially, water-soaked small spots appear. On affected leaves, the lesions are nearly circular, reddish-brown, with a halo around them. When dry, the center of the lesion ruptures. On affected fruits, dark brown lesions appear, and the fruits are prone to bending and deformation.

[Control Methods] Soil treatment: Carry out crop rotation with non-cucurbit crops for more than 3 years. Disinfect the soil, use disease-resistant varieties, rotate crops, remove diseased and residual plants, and increase the application of phosphorus and potassium fertilizers. Chemical control: Spray Bordeaux mixture 1:2:100, or 65% mancozeb 500-800 times, 80% Anthracnose Fumei wettable powder 800 times, 70% mancozeb wettable powder 400 times, or fumigate with 45% chlorothalonil smoke agent at 250 grams per mu. Use once every 7-10 days, for 3-4 consecutive times.

Cucumber Pest Control

Cucumber pests mainly include leafminers, whiteflies, and melon aphids. In the control process, the main focus should be on strengthening field management. The cucumber pest control techniques are introduced as follows:

1. Leafminer

[Damage Characteristics] After the larvae hatch, they mine and feed on the leaf mesophyll, leaving winding and tortuous feeding tracks. During the seedling stage, 2-7 leaves are often affected. In severe cases, the mining tracks are densely distributed, causing leaves to turn yellow, scorch, or fall off. The terminal end of the mine does not widen noticeably, which is a feature distinguishing this pest from Liriomyza sativae, Liriomyza huidobrensis, and Liriomyza trifolii.

[Biological Control] Release parasitic wasps such as Diglyphus isaea, Dacnusa sibirica, and Opius spp. These three parasitic wasps have a relatively high parasitism rate on leafminers. Apply insect growth regulators, which can affect adult reproduction, egg hatching, larval molting, and pupation.

[Chemical Control]

① 5% fipronil suspension concentrate, 50-100 ml per mu; 40% Qixingbao emulsifiable concentrate 600-800 times. The control timing should be during the peak occurrence period, once every 5-7 days, for 2-3 consecutive treatments.

② Insect growth regulator 5% Yitaibao 2000 times, 5% Cascade emulsifiable concentrate 2000 times. These have a sterilizing effect on adult leafminers, and after application, the hatching rate of eggs laid by adults is low.

③ Use 50% phoxim emulsifiable concentrate 1000 times and spray during the peak occurrence period, once every 5-7 days, for 2-3 consecutive times. Stop application 7 days before harvest.

2. Whitefly

[Damage Characteristics] They secrete large amounts of honeydew, seriously contaminating leaves and fruits. Leaf symptoms: Adults and larvae gather to cause damage and secrete large amounts of honeydew, seriously contaminating leaves and fruits and causing sooty mold.

[Biological Control]

① Cultivate “pest-free seedlings”: Before raising seedlings, fumigate the greenhouse to remove residual pest populations, clear weeds and crop residues, and add a layer of nylon gauze at the greenhouse vents to prevent external pest sources.

② Avoid mixed planting as much as possible: In particular, cucumbers, tomatoes, and kidney beans should not be mixed. Adjusting the production crop sequence is also an effective method, that is, arrange celery, sweet pepper, and other vegetables less damaged by whitefly in the first crop, then plant cucumbers and tomatoes in the second crop.

③ Remove old leaves and burn them: Older nymphs are mostly distributed on lower leaves. When pruning solanaceous and fruit vegetables, remove some old leaves appropriately and bury them deeply or burn them to reduce the population.

④ Encarsia formosa: Encarsia formosa can successfully control whiteflies in greenhouses. When whitefly adults are below 0.5 per plant, release Encarsia formosa adults 15 per plant every two weeks for a total of 3 times.

⑤ Yellow color has a strong trapping effect on whitefly adults: Set yellow boards in the greenhouse (1 m x 0.7 m fiberboard or cardboard, painted orange-yellow, then coated with a layer of sticky oil), using 32-34 boards per mu, with a significant effect on trapping and killing adults. Place the yellow boards between rows at a height level with the plants. For the sticky oil, generally use No. 10 machine oil mixed evenly with a little butter, and recoat once every 7-10 days. Be careful to prevent oil droplets from falling on crops and causing burn damage.

[Chemical Control]

① Use a knapsack motorized fogger or 3MF-3 knapsack multi-purpose plant protection machine to atomize 1% deltamethrin or 2.5% fenvalerate (sumicidin) oil into 0.5-5 μm droplets suspended in the air to kill adults.

② When the average number of adults is 2.7 and 6.6 per plant, spray 25% thiazinone (buprofezin) wettable powder at 100 ppm and 200 ppm 1-2 times. When adults reach 19.5 per plant, spray a mixture of buprofezin 100 ppm and bifenthrin (Talstar) 5 ppm twice.

③ Spray 2.5% deltamethrin or 20% fenvalerate (Sumicidin) emulsifiable concentrate 2000 times, once every 6-7 days, for 3 consecutive treatments.

④ Methyl kresoxim (mite-killing) wettable powder 1500 times, bifenthrin 0.8-2 g per mu. One day after application, the control effect on adults is above 99.%.

3. Melon Aphid

[Damage Characteristics] Leaves curl, seedlings wilt, and may even die. Affected old leaves wither and fall prematurely, shortening the fruiting period and causing reduced yield.

[Biological Control]

① Cultivate strong pest-free seedlings. Strictly use insect-proof nets from the seedling stage to cultivate pest-free seedlings.

② Use yellow boards to trap aphids. Take advantage of aphids' attraction to yellow color and use yellow boards to trap aphids.

③ Protect natural enemies. Such as Erigonidium graminicolum, Pardosa astrigera, Misumenops tricuspidatus, Coccinella septempunctata, Propylaea japonica, Scymnus hoffmanni, Chrysopa sinica, syrphid flies, Nabis sinoferus, minute bugs, Aphidiidae wasps, Chrysopa formosa, Chrysopa septempunctata, Cecidomyiidae, entomophthoralean fungi, etc.

[Chemical Control]

① When aphid damage is found, spray 0.65% shasuanisu 100 ml mixed with 30-40 kg of water, or Shaoguanmycin 200 times plus 0.01% washing powder, or 2.5% derris extract emulsifiable concentrate 600-800 times, or spray tobacco water (tobacco to water = 1:30-1:40).

② 20% Sule floating oil 1000 times, or 40% Juma emulsifiable concentrate 2000 times, or 21% synergistic fenvalerate · malathion (Mieshabi) emulsifiable concentrate 4000 times, or 2.5% cyhalothrin (Kung Fu) emulsifiable concentrate 3000 times, or 2.5% bifenthrin emulsifiable concentrate 3000 times, or 10% imidacloprid wettable powder 2000 times, then spray once more after 10-15 days.

To strictly control the various pests above, qualified insect-proof nets should be installed, and pests should be discovered and controlled promptly, eliminating them at the stage when they occur in spots and patches. The preferred methods are physical and biological control. During outbreaks, necessary chemical control may be chosen.