02/09/2025
Leaf Brix Experiment and Conclusions:
Chuluota,FL
*Brix numbers are % Leaf Brix (% sugar)
*Kept concise for FB
*All plants have received no synthetic fertilizer, pesticide, herbicide, fungicide etc. - Only compost last year in 2024
*limited experiment, subsequent testing to follow)
Hypothesis: Plants are more guarded against pests/diseases, the higher the sugars in their leaf (Leaf Brix)
2 plants tested - Olive ‘Arbequina’ / Passion Fruit ‘Possum Purple’
Both plants are 15 feet away from each other (very close in proximity and similar soil)
In ground plants
Olive - 7am 8.0 Brix / 2pm 16.75 Brix
Zero insect/diseases damage on plant, healthy look, new growth healthy - plant healthy and guarded
Passion Fruit - 7am 6.5 Brix / 2pm 9.5 Brix
Moderate insect damage (caterpillar), leaf discoloration, leaf curl observed - plant stressed and susceptible to insects/disease
Conclusions
Leaf Brix numbers are lower in morning than afternoon
- indicating it may be easier for insects to feed in early morning hours
Plants with Leaf Brix of 9.5 and lower are not highly guarded against insect damage and likely stressed. Potential nutrient deficiency as observed by leaf discoloration.
Plants above 16 Leaf Brix are highly guarded against insects and likely not very deficient in nutrients, as observed with very little leaf discoloration.
Since both plants are growing in close proximity, it’s indicated: either Olives are able to extract more nutrients from the ground, or have made more fungal/bacterial relationships thus receiving more water/nutrients. Also indicated Passion fruit may need higher nutrient supplementation in Central Florida soils, as compared to Olives.