Here is my favorite breed of corn: Amazon Interlocked. It goes by different names depending on the country, but it’s all the same or very similar: Piricinco in Peru, Entrelaçado in Brazil, and Pojoso in Bolivia. Coroico was the first name assigned to the group, because it was initially discovered near the Bolivian city of Coroico by the first wave of corn researchers in the 1940s. Coroico thus became a generalized name for the complex, though not technically correct. Amazon Interlocked corn grows over a wide geographic range from Loreto, Peru down to Santa Cruz, Bolivia and as far eastward as Mato Grosso, Brazil. With one exception, this is the only lineage of corn native to the southern Amazon Basin and one that traces back millennia. In many ways, it is a distinct branch on the phylogenetic tree of maize, at least in my opinion.
This particular population was developed in the 1970s by E. E. Gerrish of Cargill, Inc. as part of the same series as his Cargill Cusco. He bred 5 landraces and 1 composite of Entrelaçado from Brazil with an early Russian flint variety that contributed long day adaptation. The end result had 15/16 Brazilian Amazon genetics and 1/16 Russian flint. Gerrish released his work gratis to the public domain in 1981.
So, why am I so fond of this corn? Well, chiefly, it’s the only floury variety that doesn’t rot profusely down here (most other soft corns hail from cool + dry or hot + dry climates). That alone makes Amazon Interlocked genetics worth using. It’s not high yielding, probably because the Tupí, Carib, and Macro-Jê peoples relied more on Cassava, sweet potatoes, and meat for food (less human selection for high production). It can be rather fussy but certainly not the worst corn that I’ve grown. One has to remember that this complex was never exposed to pre-Colombian state-sponsored improvement (Cusco, Nal-Tel, Tepecintle, etc.) nor to modern crop betterment.
It’s worth noting that Brazilian Interlocked corn differs in several ways from Bolivian and – especially – Peruvian landraces: it doesn’t have nearly the frequency of bronze-brown aleurone colors found in western relatives, nor the tendency to produce multiple layers of aleurone tissue. The frequency of interlocked grain rows is also less. I suspect these differences are due to Entrelaçado having mixed some with a related corn from the Guaraní people (Avatí Morotí), one that lacks these traits. I also ponder if Mr. Gerrish intentionally removed certain colors and traits as he was developing his long day-adapted conversion. (Ex. One of the parental Brazilian landraces had blue kernels, yet the trait is completely absent in his population.)
Even though the name isn’t correct for the corn it describes, this long day adapted conversion is called Cargill Coroico. That is the name one should use in order to prevent confusion.
I have seed to sell this year. Woo hoo.
Cargill Coroico is variable in height (5 – 8 feet), maturity (50 – 65 days to bloom), color, and grain texture. Although mainly a flour corn, one could easily breed a flint or semi-floury (morocho) strain from this seed, as hard kernels segregate out frequently. Cargill Coroico is fairly resistant to northern leaf blight, highly susceptible to southern rust, and not very tolerant of drought and thick sowing. I used 680 plants for seed and hand-pollinated all of them for maximum varietal purity.