Botanical Biopesticides – Perfect Compatibility to Conventional Spraying Programs: The Case of Timorex Gold®

Biopesticides are naturally occurring products which are derived from materials such as plants, bacteria, viruses and minerals. Of these, the botanical biopesticides are considered to be attractive for plant protection. They are usually less toxic than conventional pesticides, generally affect only the target pest and closely related organisms and can greatly decrease the use of conventional pesticides, while crop yields remain high. Biopesticides used alone or in combination with conventional crop protection products have been shown to improve efficacy, enhance yield and be cost-effective. They typically do not persist in the environment, are produced from renewable sources, are safe for workers, neighbours and consumers, and provide short re-entry Intervals and short pre-harvest intervals.

Botanical biopesticides can be effectively used as part of an IPM program or a conventional spray program. They can be used either as a substitute for conventional crop protection products or be added to the spray program to increase yields from the same acreage. In many cases they have multiple modes of action and can, in season-long control programs, preserve the effectiveness of conventional pesticides and comprise an important tool in resistance management.  They act either by a direct effect against pests or pathogens (cell membrane, mitochondria, respiration (fungi), toxicity to pests) or by an indirect effect via plant defense mechanisms.

Botanical biopesticides typically have no regulated residues, thus increasing grower access to profitable export markets. They promote plant health for more attractive, healthy food. Botanical biopesticides do not pose tolerance issues, and therefore help growers manage residues to meet MRLs in food and export markets, grow to organic food standards and market “residue free” food.

The future of botanical biopesticides in playing an important role as plant protection agents among the biopesticides and the global plant protection industry seems to be very promising.  This can be achieved due to new biotechnological approaches that could be useful for obtaining bioactive products on a large scale. The recent trends of looking for new plant sources, including algae, new uses of known plants and microencapsulation of essential oils and new potent plant molecules, open a new dimension in plant protection for these natural products.

In conclusion, botanical biopesticides are effective tools for production, are renewable and sustainable, offer an improved impact profile, and reduce pesticide residues. They meet the three challenges of sustainable agriculture: they increase productivity, promote food quality and minimize impact.

Timorex Gold - a case study for botanical biopesticides

We in the Stockton Group, as developers and manufacturers of biopesticides, have focused and targeted our development efforts on plant extracts and botanical biopesticides. We have developed a unique natural fungicide, Timorex Gold®, based on an extract of the tea tree plant (Melaluca alternifolia) which contains over 100 compounds that have unique multiple modes of action. Timorex Gold® has demonstrated high efficacy against a broad spectrum of plant-pathogenic fungi with strong prophylactic and curative actions. 

The tea tree extract was approved by the European Union and is included in the positive list of the EU, in Annex I of Directive 91/414/EEC for registration of Plant Protection Products. It is classified as a low risk substance in Europe, for which establishment of maximum residue limits (MRL) is not required. Since no residue has been established, no PHI is required.

Timorex Gold’s mode of action is based on two different general mechanisms against fungi. In yeast cells and isolated mitochondria, it was reported that an extract of M. alternifolia components inhibited respiration and ion transport processes, affected mitochondria and increased membrane permeability.

Our study, using transmission electron microscopy (TEM) examination of banana leaf sections infected with black Sigatoka disease, showed that Timorex Gold-treated infected leaves contained the smallest number of fungal hyphae within the intracellular spaces of the mesophyll tissue, compared to systemic fungicides-treated leaf sections or control untreated leaves. Contrary to other treatments, Timorex Gold® caused disruption of the fungal cell membrane and destruction of the fungal cell wall of hyphae at disease development stages 4 and 5 (Fig. 1).
 

Fig. 1. Observations of banana leaf sections infected with Black Sigatoka disease under Transmission electron microscopy, revealed that Timorex Gold® caused disruption of the cell membrane and destruction of cell wall of the fungus and provided high activity in disease control

Timorex Gold® acts as a preventive and curative agent, by inhibiting various stages of the fungal life.

Resistance management

Based on the above, FRAC listed our plant extract (the active ingredient of Timorex Gold®) in target site group F7 and its MOA is classified as a: “Cell membrane disruption” classification. To date, it is the only member in this group. With FRAC’s acknowledgment, Timorex Gold® can be considered an effective tool for resistance management programs. Our above studies suggest that Timorex Gold® has a general (rather than a specific) mode of action against fungal plant pathogens. In addition, the fact that it contains multiple compounds supports a multi-site functional activity, and thus a very low or no probability for the development of resistance in plant pathogens. Timorex Gold® can be included in a spray program to avoid cross-resistance during the season. It can be rotated or tank mixed in applications with chemical products to which fungal plant pathogen populations have shown a loss of sensitivity.

Compatibility to Conventional Spraying Programs

Following large number of field and semi-commercial trials, Timorex Gold® has been widely integrated in spray programs for controlling various disease in which synthetic chemical-based fungicides provided either better or worse efficacy. For example a spray program for controlling Botrytis grey mold disease, where the chemical fungicide was applied first, followed by one or two applications of Timorex Gold®, was as effective as consecutive applications of chemical fungicide alone. This spray program for Botrytis has been demonstrated and commercially used in various countries and various crops such as grapevine, tomato, strawberries and others. In some cases Timorex Gold® provided superior disease control and was the most effective product in controlling some of the diseases. The South American leaf spot disease in coffee caused by Mycenia citricolor is an exceptional example. In this case, three foliar applications of either Timorex Gold® or a mixture containing two leading systemic fungicides, Azoxystronin + Cyproconazole,  resulted in heavy infection and leaf defoliation in the fungicides-treated plants, compared to healthy plants with new emergence of young leaves in Timorex Gold-treated coffee plants (Fig. 2).     
 

* Fig. 2. Efficacy of foliar applications of Azoxystrobin +Cyproconazole (left) and Timorex Gold (right) in controlling South American leaf spot disease on coffee plants.

Conclusions

Timorex Gold® is a natural plant extract-based fungicide with a broad spectrum activity and unique multiple modes of action. The product is an effective tool for production, is renewable and sustainable, offers an improved impact profile and reduces pesticide residues. It is not toxic to beneficial and non-target organisms and is beneficial to insects, including honey bees. Timorex Gold® is exempt from tolerance issues because there are no synthetic chemical residues and it is safe to workers and ground water. Timorex Gold^® perfectly fits the criteria of botanical biopesticides and meets the challenges of sustainable agriculture.