Biological crop protection opportunities for integrated pest management (IPM) in citrus

Citrus crops hold immense economic significance globally. Citrus pest management is one of the most dynamic aspects of pre-harvest production of citrus fruit. Chemical control has traditionally been growers’ first line of defence. However, secondary pest outbreak from the use of broad-spectrum chemicals and pest resistance has led to the development of a holistic approach called integrated pest management (IPM). IPM includes biological, cultural, and chemical control, with biocontrol as the first line of defence. This approach is developing into a key strategy that many growers worldwide adopt for preharvest pest control. It is essential for growers to be attentive in decision making when it comes to pest control. The growers need to observe the crop, analyse field situations, and make decisions based on these findings. Some of the aspects growers need to look at when making these decisions are: plant health at different stages of the crop cycle, pest and natural predator populations, soil conditions, climatic factors and the growers’ own experience.

When looking at IPM in the citrus industry specifically, a United States survey suggests that growers with greater acreage are more likely to use biocontrol options. Education is key when it comes to evaluating and understanding the benefits that biocontrol offers for the citrus crop cycle within a holistic IPM strategy.

Understanding biocontrol

Biological control, also known as biocontrol, involves the use of beneficial organisms to manage pests and diseases. In the context of citrus crops, this approach leverages predatory mites, beneficial nematodes, parasitic wasps, predatory insects, and beneficial microorganisms to regulate pest populations and maintain a healthy balance within the ecosystem. The overarching goal is to minimize reliance on chemical pesticides while preserving the integrity of the environment. Key citrus pests include mealybugs and scales, spider mites and other mites, caterpillars like false codling moth (FCM), citrus thrips and fruit fly.

Another important component of integrating biocontrol into a citrus IPM strategy is crop scouting. Monitoring and trapping can be done through the use of Koppert pheromone traps or Horiver sticky cards. Proper scouting enables growers to identify pests correctly. Correct pest identification is very important as not all parasitic wasps control all species of mealybugs. For example, the parastic wasp Anagyrus vladimiri (Citripar), will parasitise Citrus mealybug (Planococcus citri) and Vine mealybug (Planococcus ficus) well, but is not effective against Karoo thorn mealybug (Nipaecoccus viridis).

Our key biocontrol agents in the citrus crop cycle

“Timing is very important”, advises Christiaan Pretorius, technical advisor for Koppert South Africa, specialising in citrus. “For the best results growers need to start early in the season, as biocontrol takes time, unlike chemicals. The lower the pest pressure, the easier it is to gain control, so earlier is always better when it comes to biocontrol” he says. “Another important factor to take note of when incorporating biocontrol into your citrus IPM strategy is to check the withholding period and side effects of chemical sprays. Koppert’s side-effects app app is a great tool to assist in this. Make sure to check the correct label, as there is a difference between withholding period for predators, as opposed to MRL’s (minimum residue levels).”

Biofungicides

At the start of the season growers can lay the groundwork for a successful harvest with the biofungicide Trianum-P and Trianum-G, based upon the unique fungus Trichoderma harzianum. Trianum is known for its ability to promote plant growth, enhance plant health, and control soil-borne diseases. Trichoderma harzianum colonizes the root systems, where it competes with harmful pathogens for food and space, thereby reducing their populations.
From early and mid-season growers can incorporate macro-agents for biocontrol:

Parasitic wasps

Parasitic wasps are small insects that play a crucial role in natural pest control. They are called "parasitic" because they lay their eggs inside or on harmful pest insects, which eventually kills the pest. The parasitic wasp Aphytis Melinus (Aphytis) is used for the biological control of California red scale (Aonidiella aurantii), Oleander scale (Aspidiotus nerii), San José scale (Quadraspidiotus perniciosus) and other scale insects.

Another parasitic wasp, Citripar (Anagyrus vladimiri) is the natural enemy of citrus mealybug and vine mealybug. This wasp is easy to introduce and focusses on the second and third larval stages and adult mealybugs to lay their eggs in.

Predatory beetles

Predatory beetles like Cryptobug (Cryptolaemus montrouzieri) and Rhyzobug (Rhyzobius lophanthae) are renowned for their voracious appetite and primarily targets mealybugs and scales.

Predatory mites

When it comes to the control of spider mite, Spical Ulti-mite (Neoseiulus californicus) provides effective control for citrus red mite (Panonychus citri) and other spider mite species.

In control in your citrus crop cycle

Working in partnership with nature enables you as a grower to easily incorporate biocontrol into your IPM strategy. Koppert’s effective and high-quality products are easy to use, safe for users and the environment and offers the no-chemical residue solution needed for greater access to export markets. With no pre-harvest interval and limited to no resistance, a successful citrus season means being in control with Koppert.

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