Based on the symptomatology observed in the photographs, my leading suspects are Colletotrichum sp., Fusarium sp., and Capnodium sp. For this scenario, I recommend an integrated field management protocol combining good agricultural practices, microbial antagonists targeted at the different suspects, biostimulants, and soil nutritional management. This is because a multi-pathogen pattern cannot be controlled with a single biological product. I further recommend a composite soil analysis prior to starting the protocol, since nutritional and microbiological correction of the soil is a structural part of strengthening the shrub's baseline resistance.

Since this is a presumptive diagnosis, the protocol must be validated progressively:

2. implementation on a small pilot area, with weekly evaluation (containment of necrosis, reduction in fruit showing black discoloration, absence of new lesions);

3. if the response is positive, scale-up to a larger area.

Yes. Based on the new photographs and the fact that this is Robusta, I would have the Cameroon team start the following 48-hour diagnostic protocol immediately. The goal is to distinguish fungal fruit rot/anthracnose, Fusarium, coffee berry borer (CBB), and classical C. kahawae rather than guessing from appearance. Recent research supports specifically examining the interaction between CBB, Fusarium, and internal coffee-fruit rot.

48-Hour Cameroon Coffee Field Protocol

1. Select 20 trees

Choose 10 severely affected trees and 10 relatively healthy trees from the same general plantation.

Do not choose all 20 from one small spot. Spread them across the field and number them:

A01-A10= affected

H01-H10 = relatively healthy

For every tree record GPS location if possible, approximate shade level, whether the ground is wet/dry, and take one photograph of the entire tree.

This comparison between affected and relatively healthy trees is extremely important.

2. Collect four stages of berries

From the affected trees collect roughly 15-20 berries of each condition:

Stage 1 — Healthy green: completely green with no obvious lesion.

tage 2 — Early symptoms: berries just beginning to develop a brown, reddish, yellowish ol lack lesion. These may be the most diagnostically valuable samples

Stage 3 - Advanced: partially brown/black but not completely dried.

Stage 4 - Mummified: completely black, shriveled berries like those in your newest photographs.

Published CBD investigations likewise preferentially collect green berries with active black/sunken lesions, because actively advancing disease tissue is particularly useful for fungal isolation.

3. Do NOT mix everything together

Put berries from different trees and disease stages in separately labeled paper bags or clean ventilated/perforated sample bags.

For example:

Farm:

Tree: A04

Berry stage: Early lesion

Date/time:

GPS:

not put wet berries together in a tightly sealed plastic bag and leave them in the heat. That c eate secondary rot and compromise what we're trying to identi

eep diagnostic samples cool and out of direct sunlight and get them to the laboratory quickly ublished Colletotrichum sampling work has used labeled/perforated bags followed by cool storag before isolation.

4. Conduct the "50-berry test"

This is something your people can do today without a laboratory.

Randomly select 50 affected berries from several affected trees.

Beare reing each on many eriesh ys reite rack particularly dosely at the apical end the litte

Then cut the berry longitudinally through the center.

Record four things:

A. Is there an actual hole entering the berry?

B. Does a tunnel continue toward/into the coffee seed?

C. Is there a beetle, larva, egg, gallery or powder/frass inside?

D. Is the internal tissue brown/black/rotted even where the outside remains partially green?

Keep count.

For example:

50 berries opened

31 externally black

27 internally rotten

18 had definite holes

12 had seed galleries

6 contained insects/larvae

Those numbers will tell us enormously more than another photograph of an entire tree.

Research on coffee fruit rot actually used a similar principle: researchers collected fruit with CBB entrance holes, cut fruit open and recovered the insects. Importantly, subsequent USDA work found internal rot significantly greater than external rot in its Fusarium/CBB experiments, supporting the possibility that the borer's hole provides fungi access to internal fruit tissue.

5. Save any insects you find

If a tiny beetle or larva is discovered, do not throw it away.

Photograph it next to something that establishes scale. Put specimens into separate labeled containers.

We want identification specifically for:

Hypothenemus hampei — coffee berry borer.

Don't assume every circular mark is a borer hole. Many of the berries in your photographs show what may simply be their normal floral/style scar. A real tunnel continuing into the berry is much stronger evidence.

6. Laboratory work - this is the critical part

I would give the laboratory a very specific request.

Ask for fungal isolation from the advancing lesion margin AND internal diseased berry tissue, rather than merely swabbing the exterior.

Request identification for:

* Colletotrichum spp.

* Fusarium spp.

* specifically Colletotrichum kahawae

* Cercospora coffeicola

* other dominant fungi consistently isolated from symptomatic fruit
e distinction between the healthy/diseased tissue boundary is important. Published Colletorichu ork isolates tissue from this advancing margin rather than relying solely on completely decompose

tissue.

Don't accept "Colletotrichum detected" as the final answer.

This is particularly important.

There are multiple Colletotrichum organisms associated with coffee. If the laboratory identifies Colletotrichum, we need species-level molecular identification where technically possible.

And if C. kahawae is suspected, request a specific molecular confirmation rather than relying solely on colony appearance under a microscope.

lodern diagnostic research has developed PCR/qPCR approaches specifically to distinguish C. kahawa‹ rom other Colletotrichum species occurring on coffee

7. Collect soil/root-zone samples - but keep this investigation separate

For Fertile Ground's work, I would simultaneously sample the soil underneath:

10 badly affected trees versus

10 relatively healthy trees.

Keep those two populations separate.

At minimum analyze:

pH, organic matter, N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu, B, soil moisture and EC.

Then perform the microbial/genomic analysis you normally use on representative samples.

This is a parallel investigation. I would not assume that a soil deficiency or microbial imbalance caused the black berries. We first need to establish the pathogen/insect component independently.

8. Do not treat the experimental trees yet

This is important.

For these 20 diagnostic trees, don't introduce bacteria, fungicide, insecticide or fertilizer until the initial samples have been taken.

Otherwise we contaminate our baseline.

Once everything has been sampled, the larger plantation can begin appropriate sanitation while we establish treatment plots.

After sampling

Remove and collect badly diseased/mummified berries from the production area rather than allowing them to accumulate indefinitely on trees or the ground. But don't destroy every diseased berry until sufficient laboratory samples have been preserved.

What I particularly want photographed

The next photographs I want from Cameroon are different from the ones we've been receiving.

Have someone take 10-15 affected berries and photograph each berry twice:

Photograph A: extreme close-up of the suspected entrance/lesion.

Photograph B: the exact same berry cut longitudinally directly through that spot.

That will allow us to see whether we're looking at an external fungal lesion, an insect entrance tunnel, internal rot—or potentially all three.

What would constitute a breakthrough

There are three results that would immediately change our strategy.

• If most damaged berries have CBB tunnels: insect-mediated injury becomes a major component.

* If berries have substantial internal rot without borer galleries: fungal fruit rot becomes even more compelling.

* If Colletotrichum repeatedly comes from early lesions and Fusarium predominantly from advanced/internal lesions: that would be remarkably consistent with the emerging coffee-fruit-rot model reported in recent research.

And if molecular testing identifies C. kahawae, we change direction again and treat the situation as confirmed CBD rather than assuming that Robusta and the lower elevation rule it out.

I would start this today. The highest-value samples are not necessarily the completely black berries-the berries at the very beginning of the transition from healthy green to diseased may give the microbiologist the clearest opportunity to identify the primary pathogen rather than organisms that colonized the fruit after it died.

Once the first 50-berry cut-open results come back, send me the numbers and close-up photographs. I can use those results to narrow the diagnosis substantially and then design the Fertile Ground treatment trial-control, conventional treatment, beneficial bacteria, and combined treatment—so we can determine scientifically whether the biological program actually stops the losses.