What are some common pests that can affect tissue culture plants?

Insects and mites may discolor and scar leaf, flower, and fruit surfaces; distort plant parts; or vector plant pathogens. Thrips are insect pest species that feed by puncturing the epidermal (outer) layer of host tissue.

Damage caused by thrips typically appears on young leaves, flowers, and fruits. They also produce black varnishlike flecks of frass (excrement).

Thrips

Thrips are a common pest of many garden and landscape plants, including some commonly used tissue culture crops such as apple and sweet cherry. They are tiny insects with piercing mouth parts that can damage a variety of plant tissues. When populations become excessive, thrips can cause significant problems with these plants and spread disease.

Identifying and controlling wholesale tissue culture plants is essential to successful tissue culture production. Nonprofessionals may be able to distinguish between certain thrip species based on behavior, body appearance and host plant characteristics; however, it is important to obtain accurate identification of a pest species from an expert.

For example, avocado thrips superficially scar the skin of avocado fruit; onion thrips do not damage the leaves or fruits of onions. Western flower thrips damage rose petals and cause distorted bloom buds.

These insect species also vector Impatiens necrotic spot virus and Tomato spotted wilt virus, which can severely damage or kill some vegetable crops. Using resistant varieties and fungicides can help manage these diseases.

Controlling thrips requires a combination of cultural and chemical methods, as well as the use of effective insecticides to control infestations. Neonicotinoids are effective against thrips, but the effectiveness of these insecticides varies by the product and plant location.

Systemic insecticides such as acephate (Bayer Advanced Tree and Shrub Insect Control, Merit), dichlorvos (Safari), imidacloprid (Bayer Advanced Fruit & Vegetable Insect Control, Bayer) and dinotefuran (Safari) are effective against thrips in the field. Application of a soil drench or injection of these chemicals generally requires a longer time to provide thrips control than trunk spray or air application of a neonicotinoid pesticide.

The use of natural enemies such as green lacewings, minute pirate bugs, mites and parasitic wasps also can help to control thrips. These predators are beneficial because they eat thrips before they cause damage to host plants, helping to reduce thrips population sizes.

A properly managed thrips program includes identifying the thrips that are present, conducting routine sampling to determine the level of a thrips population and developing a control strategy to reduce or eliminate the population. This will help to maintain a healthy, pest-free environment.

Spider Mites

Spider mites are a common pest in a variety of plants and can be especially damaging to tissue culture plants. They cause clusters of tiny white or yellow spots on foliage, which look like stippled areas and eventually lead to complete defoliation and even plant death.

These bugs also have piercing-sucking mouthparts that extract fluids from the cells of leaves. This causes a loss of hydration and water content, and leaves become shriveled. As a result, plants are weakened and their yields reduced. They are particularly damaging to fruit trees and shrubs, and can also infest hydroponic setups and houseplants.

Under optimum conditions, spider mites can develop from eggs to adults in less than a week. In the same time, they can multiply rapidly and produce several overlapping generations per year.

Females lay dozens of eggs on host plants, and these may hatch into six-legged larvae within a few days. These may continue feeding for a few more days before turning into eight-legged nymphs. These nymphs feed for a few more days before they transform into adult spider mites.

Almost too small to be seen by the naked eye, adult spider mites are green or brown and measure 1/50-in in size with four sets of legs. They have two dark spots on the back and are often translucent, but can be brown or orange-red as well.

As they mature, spider mites bury themselves in fine webs on their host plants. This webbing is very dense, and prevents other herbivores from feeding on the plant.

Insects that consume these mites are usually not harmed by the mites’ web. However, they do tend to avoid infested plants because the mites’ web induces or suppresses certain plant defences (Ferragut and Escudero 1999; Sarmento et al. 2011a).

We investigated whether spider mites’ webs affect the preferences and performance of a whitefly, Bemisia tabaci. We found that plants covered with a spider-mite web had significantly lower preference and juvenile survival than clean plants or plants attacked by Tetranychus urticae or Tetranychus evansi without web (Fig. 2, 3a). This indicates that the spider-mite web serves to suppress certain plant defences and thus reduce competition with later-arriving herbivores.

Black Spot

Black Spot is a fungal disease that can affect many species of plants. It can cause a variety of problems for tissue culture plants, including decreased plant quality and reduced yields. It also has the potential to contaminate other plant parts, including soil and air, which can lead to further damage.

This fungal disease is not particularly common in Australia, but it can become a problem if it is a severe enough threat to the health of your tissue culture plants. There are several fungicides that can be used to control this disease.

Using Safer(r) Brand Garden Fungicide to treat this disease is a good way to help prevent it from spreading and damaging your tissue culture plants. You can spray it on your plants when you notice the signs of black spot or a month later at intervals of 7 to 10 days to keep your garden healthy and free from this pest.

The fungus that causes this disease can live in the air or on pruning tools, so it is important to disinfect your tools before and after using them. This will eliminate the chance for spores to survive in them and spread the disease.

Black spot typically develops in warm, wet weather. It is most common on young, succulent vine tissues and canes but will also infect mature tissues.

Infected leaves develop irregular black spots that can be up to 1/2 inch in diameter. These spots are circular or elliptical in shape and often have fringed borders. As the disease progresses, the spots merge and the entire leaf becomes infected. Leaves are eventually dropped and canes begin to die.

This disease is primarily a problem for roses and is most common in mild climates. A number of rose cultivars have been developed that are resistant to this fungus.

It is a good idea to plant roses in areas that are dry and well-ventilated. This will allow the leaves to dry more quickly after rain and reduce the opportunity for black spot infections to occur.

Another effective management strategy is to remove and prune infected canes. This will dramatically slow initial spring infections and will also encourage better air circulation, which can help to speed up the drying of infected leaf surfaces.

Other Pests

A variety of insects, fungi, and bacteria can cause damage to tissue culture plants. Understanding how these organisms affect a plant can help you determine whether an insect or microorganism is the culprit behind a plant problem.

Many insect and pathogen species have developed specialized mechanisms to access the phloem, a nutrient-rich tissue deep inside a plant that transports photosynthates from leaves to sinks (e.g., buds, flowers, seeds and roots). Consequently, phloem-infecting pathogens can wreak havoc on a plant’s vital organs including its stem, root, and leaf.

The best way to prevent these organisms is to control the source of entry. This includes repairing damaged screens and properly sealing windows and doors, as well as identifying and controlling pests that already have established residence in your home.

Another important part of pest management is to identify and eliminate potential habitats that the pests can use for shelter, food, and breeding. These include mulch, wood, and other materials around the home that the insect or microorganism can use as a hideout.

Some of the most common pests that can affect plant culture experiments include nematodes, mites, ants, and flies. All of these can be a nuisance and cause damage to your experiment. The best ways to prevent these pests are to inspect your lab for signs of an infestation, remove any potentially contaminated items from your work area, and use insecticides sparingly.