5 Pests to I.D. to Prevent Diseases in Hydroponic Cultivation

1. Red spider mite: Tetranychus urticae (Arachnid Class-Order Acari).

It is a small-sized mite, measuring approximately 0.6 mm; its presence can be recognized with the naked eye as small reddish spots on the leaves or the stems. During the summer, they have a greenish coloration with two darker spots on the sides, but when winter approaches, the coloration is deep red, being the form of resistance. Under optimal temperature conditions (23-30ºC), they develop their cycle (Egg-Larva-Protoninfa-Deutoninfa-Adult) between 8-14 days. Each female can live 20-28 days, and in that period, she lays 100-200 eggs. The abundant colonies of red arañuela live generally grouped in the underside of the leaves. They produce silk threads in large quantities, which serve as protection against natural enemies and chemical controls with acaricides.

Damages

It is a very polyphagous mite that can attack horticultural, floricultural, ornamental species, etc. The buccal structure consists of 2 chelycers with which it punctures superficial cells, feeds on the content or cellular juice mainly of leaves, absorbing it cell by cell, leaving a small yellowish spot (chlorotic scores) that contrasts with the usual green of the leaf. Severe attacks cause widespread discoloration of the leaves with subsequent death of the tissues (necrosis), evidencing a brown color, dehydrated causing intense defoliation. With high temperatures and drought, the abundant fabric with which the leaves are wrapped reduces photosynthesis and even kills the plant. Attacks occur in foci, and multiplication is favored by the functional nutritional status of plants, specifically concerning nitrogen. Direct damage consists of the destruction of epidermal tissue, deformation, and death of leaves and shoots, general weakening, and death of plants, while the indirect ones lead to the loss of commercial quality.

Driving options

Keep without weeds inside and outside the premises. Disinfect work utensils. In the presence of high populations of mites, the application of sulfur-based products is recommended in the afternoon. Use vegetable preparations and acaricides allowed in organic crops. Take into account the natural presence of acarófagos mites.

2. Thrips: Frankliniella (Class Insecta-Order Tisanócopio)

They are small insects, reaching between 1-2 mm in length, elongated body from yellowish to dark brown. The buccal structure consists of a buccal cone (3-stiletto-sucking buccal apparatus), with which they pierce/gnaw the epidermis, inject saliva and feed on cellular juices, the cells thus emptied, are filled with air taking the attacked area silver color. Most species are polyphagous attacking horticultural, floricultural, fruit, weed, etc. crops. Biological cycle (Egg, Nymph1, Nymph2, Prepupa, Pupa and Adult) is of variable duration, but the most important species, such as:

• Frankliniella schultzei, "thrips of the flowers";

• Thrips tabaci, "onion thrips";

• Frankliniella occidentalis, "Californian thrips of flowers",

can fulfill it in 15 days or less, favoring high temperatures and low humidity, resulting in more than ten generations per year. The eggs are embedded by the female within the plant tissue, laying up to 300 eggs for one month. Pupal states do not cause damage, are inactive, and are hidden at the base of the plant.

Damages

Direct damage is done by oviposition and feeding: Females cause a type of injury by embedding their spawning; Reniform eggs are placed under the epidermis and covered by feces, giving the appearance of "dirty leaves." Chlorotic or corky tissue will be seen around the incision area. Another damage is done with the oral apparatus, both adults and nymphs, resulting in elongated silver areas, because the attacked cells are filled with air when their cellular juices are scraped and emptied, with subsequent necrosis and defoliation. Direct damage is done by attacking tender tissues of buds, leaves, flowers, and growing fruits, using spots in the form of silver streaks, then brown-colored necrosis. In critical attacks, they produce deformation of buds and abortion of flowers and fruits. Indirect damage is done by being vectors of viral diseases, in horticultural and floricultural crops predominates the transmission of the Black Plague virus (TSWV) that is acquired by the Nymphs1 when attacking a diseased plant and is transmitted by adults every time feed Sick plants with black plague will appear yellowish, dwarf, with stained, deformed leaves; with abortion of flower buds and stained fruits, among other symptoms.

Driving options

Destroy crop residues inside and around the greenhouse. Natural enemies: stimulate the presence of beneficial or chinitas vaquitas (larvae and adults of coccinellid beetle insects), crisopas (neoptera insects larvae) and Orius bug (genus of nymphs and Heteroptera Hemiptera insects adults) that are efficient thrips, predators. The adult tisanópteros, despite short flights, are highly invasive. It is possible to detect their presence in time and reduce populations with the use of yellow or blue sticky traps since they are strongly attracted to these colors. Use vegetable preparations and insecticides allowed in organic crops. Protect the installations with anti-insect polyethylene meshes, as a physical block.

3. Aphids: Myzus persicae, Aphis fabae, Macrosiphum euphorbiae, Aulacorthum solani, Brevicoryne brassicas, Uroleucon ambrosiae. (Class Insecta-Order Hemiptera-Flia. Affiliates)

Aphids or aphids are small insects, they reach between 1.5 to 4.5 mm in length, with a globose and soft body, of variable colors such as light or dark green, yellowish, reddish, grayish or black. With the sucking mouth buccal apparatus, they puncture, inject saliva with sometimes toxic substances and extract sap from leaves and buds by suction. The numerous colonies live forming masses of insect populations, mainly on growing tissues with the presence of young people and adults with or without wings. Most aphids remove large amounts of molasses through the filter chamber of the digestive system allowing the development of fumagina fungi, which by covering the foliage, prevents photosynthesis and the action of chemical controls. Females, without having been fertilized, can give birth to young embryos called nymphs, which, after four nymphal stages, become adults. They develop the cycle in a few days; for example, the Myzus aphid persicae under optimal conditions at 24 ° C can perform a complete cycle in 7 days; The females can give birth to 400 nymphs daughters in 15 days. When plant food is scarce, or there is overpopulation, winged adult individuals emerge that migrate to other plants in search of new crops.

Damages

Most aphid species are polyphagous from horticultural, floricultural, cereal, fruit crops, etc., while some are specific to certain botanical groups (e.g., B. brassicas in Brassicaceae). When aphid populations are abundant, the extraction of sap in large quantities weakens the plant until it can cause death. Another direct observable damage consists of the deformation of leaves and buds, causing the loss of flowers and fruits. Indirect damage consists of the production of sugary liquid (molasses) on which the fumagina fungus develops, which is a black-looking powdery covering, on the surface of the leaves, which decreases the photosynthetic capacity and foliar evapotranspiration. Another indirect damage results when the crops get sick because they can transmit viruses to the plants, which causes significant economic losses since the crop can be wholly lost.

Driving options

Controls that apply to other pests usually eliminate aphids. Several species of natural enemies (predators, parasitoids, and pathogens) regulate their populations. Among the most important predators are larvae and adults of beneficial cows, larvae of crisopas, young nymphs, and adults of bed bugs and larvae of syrphid flies. Also, there are several species of parasitoid wasps. The use of yellow sticky traps is recommended. Protect the installations with anti-insect polyethylene meshes, as a physical block. If necessary, apply selective chemical control with products that do not affect this beneficial fauna.

4. Whiteflies: Trialeurodes vaporariorum, Bemisia tabaci (Insecta Class-Order Hemiptera-Flia. Aleirodids)

Delicate and small insects measure 1 to 2 mm in length. They present the body and the two pairs of wings covered with a white waxy substance, which is why they are known as "whiteflies." They are considered primary pests in greenhouses, polyphagous, attacking all types of horticultural and floricultural cultivation mainly. Whiteflies are pests of high reproductive potential, and Bemisia has different biological types. The adults, like the young nymphs, have a buccal-sucking mouth apparatus; They are usually located on the underside of the leaves where they feed on sap. The female, after being fertilized, broods for 3 to 6 weeks, placing up to 300 small eggs, whitish and oval with peduncle using which it fixes them to the underside of the leaves in circles or semicircles. From them, nymphs are born that at first are transparent and then light green. They are mobile-only in the first nymph stage, the subsequent nymph II and III are immobile and represent the state of highest consumption. Nymph IV, also called pupa, is a state of rest, during which they do not feed. The complete cycle is fulfilled in 20 to 30 days at an optimum temperature of 21-24ºC with a maximum of 32ºC. In greenhouse conditions, they can develop up to 10 generations/year.

Damages

White mosquitoes congregate in large quantities on the underside of the upper leaves and generally fly towards the beam when disturbed. Adults and eggs are detected in young leaves, while nymphs are typically located in old leaves. Nymphs and adults cause direct damage by sap extraction and injection of toxic saliva into the plant. When there are large populations, they cause weakening, dehydration, growth arrest, death of leaves, and decreased yield. Indirect damage consists of the production of sugary liquid (molasses) by the digestive system, on which the fumagina fungus develops, which covers the surface of leaves and fruits black. Although the most significant damages are caused by the transmission of viruses that cause reduced performance and small fruits. Due to the development of imaging, commercial quality and extra expense are lost due to the washing that must be carried out on the fruits

Driving options

It is recommended as a cultural control to use anti-insect mesh, the placement of yellow plastic sticky traps in different crop sites, for monitoring and population decline, the removal of plant debris, and if there were weeds nearby that act as reservoirs. Use vegetable preparations and insecticides allowed in organic crops with low populations. Applications through conventional chemical control will be carried out when the installation of the pest begins in young crops and, at times, conducive to their development. When the crop is advanced and the time is not conducive, interventions may be delayed. In tomato undercover with traditional management, chemical control is suggested when more than five adult Bemisia per leaf and more than 10 Trialeurodes are observed. Take into account the presence of biological control organisms such as wasps that parasitize pupae of the flies; they appear black or deep orange; Myriad predatory bedbugs (Tupiocoris cucurbitaceous), Orius; as well as crisp as among others.

5. Cartoonist: Liriomyza spp. (Class Insecta-Order Diptera-Flia. Agromycids)

It is a polyphagous pest of habitual presence in horticultural and floricultural crops. The adults of the "cartoonist" or "leaf miner" are small flies, measuring 2-3 mm in length. The body is bright black with yellow, dorsally has a characteristic bright yellow triangular spot between the wings. Adults are very good fliers and move around plants with rapid, irregular movements. The females pierce the young leaves forming the so-called "pits" and ovine an egg inside each one of them, feeding on the liquid that emanates from the bites. In seedlings, the oviposition begins in the basal leaves, being invaluable to the observation and only visible when the damage is established. After a few days, the larvae are born that begin to feed on the mesophyll tissue of the plant, below the upper surface of the leaf. The larvae reach about 2 to 3.5 mm in length, are yellowish, undermine the leaves, and move forward as they grow. The larvae that emerge from the internal galleries after having completed three stages, in general, they are transformed into pupae or puparium in the form of a barrel, at the end of the gallery, being temporarily attached, and then fall. Adults born from them live for 10 to 20 days. The biological cycle of the sketcher or leaf miner can be as short as 16 days at 25 ° C, an average of 21 being estimated, depending on the host plant and the temperature. They can perform 9-10 generations/year.

Damages

The main cause of damage to the plant is the galleries that make the larvae in the leaves. The larvae feed by mining between the upper and lower leaf surfaces creating sinuous tunnels that are initially small and narrow but increase in size as the larvae grow. In the beginning, the galleries are almost transparent, but with time, they acquire a greenish-yellow hue and subsequently become necrotic. These mines can cause direct damage to the seedlings by removing chlorophyll and reducing the photosynthetic capacity of the plants. The attacked foliage will appear necrotic, and there will be defoliation. Oviposition-feeding mines and pits also open entrances for pathogenic organisms. In plants with an excessive number of galleries, it can cause the leaves to be dry, which results in sunburn on the fruits and reduction in yield and quality. In severe infestations, leaf mines can cause the death of plants; as well as, it can cause leaf fall when the density of the pest is very high, producing economic losses. In high populations, it can cause damage to 100% of the foliage, which causes the defoliation of the crop

Driving options

Keep weed-free culture beds. Place yellow or white adhesive plastic traps. It is convenient to use anti-insect mesh. Excessive chemical control of pests in the greenhouse causes stronger damage to crops due to the presence of miners due to the elimination of their natural parasitoids, for example, the wasp Diglyphus sp. that attacks fly larvae. Several crops must be sown simultaneously in the greenhouse, to diversify the crops. If necessary, apply the biological insecticide based on Bacillus thuringiensis, a bacterium that infects and kills the larvae. It is safe for the environment, has a residual effect of 10 days, and is not toxic to other organisms. The programmed elimination of the foliage, using the pruning of the crop during his development, diminishes the infestation of the larvae of Minador of the leaf significantly. For this, the removed leaves are collected in plastic bags and destroyed.