Narrowing plant problems by observed signs
Narrowing the list of possible problems for a crop by observed signs. No diagnosis is made: the number of matched signs and the source description are given.
Quantities
| Symbol | Quantity | Unit |
|---|---|---|
N | source entries for the crop | entries |
k | signs selected | signs |
m | signs matched | signs |
p | share of remaining entries carrying a sign | dimensionless |
Formulas
Entry selection
an entry is shown ⟺ it carries all k selected signs
Conditions are conjunctive, not disjunctive: the selection describes what the person sees, not a list of guesses. The value m equals k for every entry shown.
Choice of the next question
|2p − 1| is minimised
The question asked is the one splitting the remaining entries most evenly. A question every remaining entry answers the same way (p = 0 or p = 1) is not asked: it narrows nothing. The order of questions therefore differs between crops.
The source and its licence
Problem descriptions are taken from PlantVillage (Pennsylvania State University). The site text is licensed CC BY-SA 3.0; attribution is required and is shown with every entry. The source photographs are not used: the text carries one licence but each image carries its own, and some of them forbid commercial use. Images are taken from Wikimedia Commons by the scientific name of the causal organism.
Splitting the text into signs is done by the application
The source describes symptoms as running text and does not annotate them. A sign counts as mentioned when one of the English words assigned to it occurs in the entry text; the word lists are shown in full in the application. This is an index into the source, not a statement by the source, which is why the entry text is quoted alongside it verbatim.
What the application does not compute
Neither probability nor a likelihood ranking is computed. The source lists the signs of a disease and assigns them no weights, and assigning weights in the application would introduce a quantity the source does not carry. The same sign belongs to several causes: yellowing of the lower leaves is described for nitrogen deficiency, for watering faults, for wilt and for spider mite.
Link to the plant protection registry
An entry is linked to a pest catalogue record only on an exact match of scientific name, English name or recorded synonym. A match exists for a minority of entries: the catalogue is built on a plant protection registry whose rows are Russian disease names without a species. Where no match exists, a search by name is offered instead.
Applicability and limitations
- 34 of the 40 catalogue crops are covered; for six crops the source has no page.
- Entries are shown in the source language until a translation is made.
- Signs are detected in the English text; the sign dictionary is compiled by the application.
- Entries in which no sign was found are not removed from the list.
- An image is not available for every entry; physiological disorders have no causal organism and hence no image by species name.
- Confirmation is made by the person; the result is not written to the care journal.
Sources
- PlantVillage, Pennsylvania State University. PlantVillage: diseases and pests by crop. Описания проблем растений по культурам: признаки, причина, что делают. Текст сайта под лицензией CC BY-SA 3.0 («All Content … is licensed under the Creative Commons Attribution-ShareAlike 3.0 License, unless marked otherwise», условия использования, раздел 8). Фотографии источника не берутся: у каждой своя лицензия, и треть запрещает коммерческое использование — full text open Open