The bulkiness of cannabis, and its relatively low value, make it a crop best grown near the market.Tracking crops is difficult, but easier, thanks to spy satellites, than tracking chemicals.
Furthermore, shifting to crops is difficult due to a shortage of labour lack of sufficient traction animals, and unreliable rainfall to cultivate crops.
However, due to its self-incompatibility, populations of doubled haploid lines (DHs) or recombinant inbred lines (RILs) favorable for QTL mapping in other crops are difficult to develop in ryegrass.
Furthermore, generalisation of findings regarding gene regulation from model to crop plants is difficult because most major crops have considerably more complex genomes.
Monitoring alien introgressions in crop plants is difficult due to the lack of genetic and molecular mapping information on the wild crop relatives.
Managing crop viruses is difficult due to complex interactions among vectors, reservoirs, and mediating factors such as land cover.
Its crop establishment is difficult to control as growers attempt to drill at minimum cost, and the weather may be hot, dry, or with rainstorms.
Accordingly, some remnant stands of natural forests are mainly confined to religious sites, along rivers and streams, and on peaks of hills where crop cultivation is difficult in the highlands of Ethiopia (Warra et al. 2013).
Although crop rotation can sometimes serve as a viable disease control option in annual crops, it is difficult to apply this practice in perennial tree crop production systems due to limited available orchard sites and long life cycle of a commercial orchard.
