Development of a natural spray against camellia petal blight

A project proposal by:

Associate Prof Paul DijkwelSchool of Fundamental SciencesMassey UniversityPalmerston NorthDr. Matthew Denton-GilesWaireka Research CenterCorteva™ AgriscienceNew Plymouth

May 2019


Plant diseases caused by fungi belonging to the family sclerotiniaceae cause, amongst others, grey and white mould. These fungi affect over 500 different plant species including grape, strawberry and bean. Well-known from our gardens is the disease called petal blight, which causes premature browning and fall of blooms of camellia species and hybrids (figure 1). Since 2011, Paul Dijkwel has been leading the camellia petal blight research programme at Massey University. The disease is caused by Ciborina camilliae, and only affects camellia plants. However, camellia species with a high degree of petal blight resistance exist. Using the latest technologies, we have discovered the basis of petal blight resistance. We found that a resistant species, Camellia lutchuensis, rapidly produces six biological compounds when challenged with the fungus. Crucially, when we sprayed the blooms of a highly susceptible camellia plant with the compounds, three compounds completely inhibited infection, two strongly limited infection and one did not affect development of the disease (see figure 2).


Project proposal


-We propose to develop a spray against Ciborinia camelliae that includes one or more of the discovered biological compounds and additives that allows the compounds to spread and stick onto the surface of camellia petals. 

-We also propose that the spray will have wider applicability to protect against other fungi of the family sclerotiniaceae and we will test the effect of the spray against Botrytis cinerea

Work plan: 

As part of the proposed PhD research project, we will test a wide variety of biological compound combinations for their effectiveness in protecting camellia blooms against Ciborinia camelliae infection. In addition to the compounds, we will also test additives to help with the spread and penetration of the compounds (surfactants) and chemicals that will help the compound to stick to the petal surface and resist being washed away by rain. 

Concurrently, we will test the spray formulations on a generalist fungus of the family sclerotiniaceae, Botrytis cinerea. This fungus can infect many plants, including grape and strawberry (grey rot), but it also infects camellia blooms and the model plant species Arabidopsis. We will apply the sprays on both camellia blooms and Arabidopsis plants. For this part of the project we have available a DeVries 3rd generation research sprayer (figure 3). This equipment will allow a consistent and reproducible treatment of the blooms.

In addition, by using modern technology optimized by us, we will discover in what way the compounds inhibit infection and this will allow us to better predict how the compounds will protect other plant species against a wide variety of fungal pathogen. 

The partners: 

Massey University has acquired intricate knowledge on camellia petal blight and plant-fungal interactions and is therefore ideally suited to carry out the research. The proposed research is neatly complemented by Corteva Agriscience (the newly merged Dow AgroSciences and DuPont Crop Protection), a world leader in the field of fungicides who will provide expertise and facilities for the development of these natural fungicide products. The combination assures sound scientific rigor combined with intricate knowledge to develop products for use in gardens and horticulture.

Benefits for Camellia growers world-wide

-The project addresses a problem that many camellia growers face during the winter season.

-By making use of natural products produced by resistant plants, we strive to help develop a safe and environmentally friendly product. 

-Results obtained will be released to the public domain so that any benefit can go directly back to those who fund this project: the public.

-The project also addresses two devastating fungal diseases, white and grey rot.  


The PhD project will take place over a period of 3.5 years, with the first three years dedicated to experiments and the final half year for thesis writing. We anticipate that the student will be able to start their project at the beginning of 2020 and finish mid-2023. The timeline below shows what aspects of the proposed work will be done over the course of the PhD project.

  1. Spray formulations will be developed in year one and refined in year two for spray tests on camellia petals and Arabidopsis plants during the winter period. 
  2. In the third year we will do field tests on camellia plants during season.
  3. Field test to determine the effect of the optimized formulas on Botrytis cinerea infection.
  4. As part of the spray tests in the first year, we will analyse the effects of the sprays on both fungi, Ciborinia camilliae and Botrytis cinerea. This will help refine the spray formulations.
  5. By making Botrytis cinerea mutants and then testing the effect of the mutants on infection, we will be able to determine how the natural compounds inhibit infection.
  6. By comparing Botrytis cinerea with other fungi, we will be able to predict how the spray formulations will work to protect plants from other fungal diseases.
  7. Thesis writing and submission.


We seek funding for a stipend in line with Massey University PhD scholarships (NZ$25,000 pa plus NZ$8,000 pa fees). Frequent travel and accommodation is required for travel between Massey University and Corteva Agriscience (NZ$2,500 pa). The work includes expensive molecular biology and genomics research (NZ$10,000 pa). The fourth year (6 months stipend at NZ$12,500) does not require consumables and travel and fees will be requested from Massey University.


Stipend plus fees                                NZ$33,000 for each of 3.5 years          NZ$ 115,000

Travel and accommodation                 NZ$2,500   for each of 3 years             NZ$     7,500

Consumables                                       NZ$10,000 for each of 3 years             NZ$   30,000

                                                            TOTAL          =                                    NZ$ 152,500


Camellia Memorial Trust (obtained NZ$ 5,000 for 3 years)                           NZ$   15,000

L.A. Alexander Educational Trust (obtained NZ$ 20,000 for 3 years)            NZ$   60,000

Massey University (obtained)                                                                                     NZ$   24,000

Additional funds still to obtain                                                                         NZ$   53,500

                                                            TOTAL          =                                    NZ$ 152,500

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