In horticulture there are always challenges when growing a crop. One of the most common challenges faced by growers is the risk of pest incidence on their crop. But, how can we prevent pests? How can we control an infected crop?
Pest management is a vast and delicate topic. In this article we will share some general recommendations in prevention, monitoring and control of most common pests in controlled environment agriculture for common crops.
Fungi and Bacteria
Some of the most common pests in controlled environment agriculture when growing any kind of crop are bacteria and fungi. The development of these microorganisms can be triggered by our greenhouse environment.
In order to avoid incidence of fungi and bacteria, in general, it is necessary to control sanitation and environmental conditions. Commonly used sanitation products are Zerotol 2.0 (OMRI listed) and Oxidate 5.0 made by Biosafe Systems. If you follow the labeled instructions, ZeroTol 2.0 is safe to use on live plants starting at propagation. Optimum humidity levels to promote germination of spores of most fungi are between 95% to 98%. Therefore, it is important to monitor our greenhouse and humidity levels in all areas. Sometimes small areas can have high humidity levels and trigger the development of fungi or bacterial diseases. Also, high crop density can also create conditions to develop fungi and bacteria.
Remember plants transpire, and if a high number of plants are growing together, transpiration will create high humidity conditions at canopy levels making it easier for microorganisms to flourish. To maintain uniform humidity conditions in our greenhouse it is necessary to keep consistent airflow at canopy level and throughout the greenhouse.
It’s recommended to keep wind velocity between 0.3 to 1 m/s to. Too little airflow can promote conditions to develop unwanted microorganisms. Both humidity and airflow can be monitored with sensors such as those by 30MHz. Another recommendation is to harvest all fruits and plants on time because old fruits and leaves can easily spread diseases in your crop.
Regarding sanitation, always try to keep your greenhouse as clean as possible. Use products for sanitizing your greenhouse between crop cycles. Do not let water accumulate in areas that are supposed to be dry. Some fungi have spores that can move in water. Also clean all your equipment with hydrogen peroxide (3%) to avoid bacterial growth. You can also use this technique in your water reservoir to prevent or manage unwanted microorganisms in your plant’s roots.
Insects and Arachnids
Whiteflies are small flies usually found under-surface leaves of many crops. This insect is a carrier of viruses that can infect crops such as tomato, cucurbitaceous species, sweet potato and several other vegetable crops. Symptoms include yellowing and leaf curling. Also, feeding by nymphs can induce physiological disorders such as irregular ripening in tomatoes and silverleaf in cucurbits. Whiteflies also produce a shiny, sticky sheen known as “honeydew” that provides an ideal substrate for sooty mold growth. This can affect the leaves’ ability to perform photosynthesis.
Thrips affect several greenhouse crops, such as sweet peppers, strawberries, melons, cucumbers and tomatoes. Thrips can cause direct and indirect damage by scratching plant tissues and sucking sap. This process ends up reducing chlorophyll levels which cause chlorosis and loss of leaves. Other symptoms can also be found in flowers where thrips cause light spots on petals and necrosis. Fruits can present silvering color in peppers, bronzing in strawberry, small perforations in tomato and general fruit deformation. These insects can also trigger diseases such as Botrytis and Alternaria.
One of the biggest problems caused by thrips is the potential transfer of the disease Tomato Spotted Wilt Virus. Thrips are mainly found in the middle and upper parts of the plant. In general they “hide” inside flowers, where they are nourished by their favorite food, pollen. A way to scout them is to take a white sheet of paper and gently shake flowers over the paper. They can then easily be viewed and identified.
- Neoseuilus cucumeris mites from Biobee
- Amblyseius swirskii mites from Biobee
- Entrust and Entrust SC
- Pyganic EC
- Horiver Blue Sticky trap (for monitoring)
Spider mites are tiny spiders that can be found in common crops used in controlled environment agriculture. The problem with spider mites starts when this arachnid lays its eggs on the leaves. Nymphs and adults suck the cell contents from the leaves of the host plant cell by cell, leaving tiny, pale spots or scars where the green epidermal tissue has been destroyed.
When infestation by spider mites is extreme, plants will reduce photosynthesis and damage can even cause plants to eventually die. Also viruses can be transmitted, although not common. These pests rapidly multiply, so catching them early is very important. They are normally present on the undersides of leaves, but will move to the tops of leaves when plants are heavily infested.
- Phytoseiulus persimilis by Biobee
- OHP Pycana™ Insecticide/Miticide
- Floramite SC Insecticide
- Shuttle O Miticide
Aphids are soft-bodied small insects damaging common crops such as lettuce, tomato, strawberry etc. They very rapidly reproduce, so you should always scout and act fast when spotted. Nymphs and adults can suck nutrients (sap) from crops and disturb the plant hormone function. Symptoms include deformed leaves, photosynthesis reduction and sticky leaves and fruits (from honeydew) which can trigger fungi or bacterial growth. Aphids are also responsible for transmitting Cucumber Mosaic Virus.
- Aphidius colemani by Biobee
- Aphidoletes aphidimyza by Biobee
- Avid 0.15 EC Miticide Insecticide
At Hort Americas we offer multiple options to control and prevent pests in our crop. Please be sure to properly identify your pest and follow all product labels/ instructions.
Contact us with questions- we’re here to help whether you are a traditional or organic grower, we have great options for you!