Genetically modified trees are not being used to improve trees, their positive things are genetically modified trees are designed to be hardier than nature trees, because of that they are more likely to survive than their unmodified counterparts. For example, in Hawaii, a new pest-resistant species of papaya tree has been developed in response to ring-spot virus infections that have repeatedly damaged the native papaya-tree population but planting the genetically modified papayas has largely put an end to the ring-spot problem. 
But in the lecture, it says that if there are some problems in the place that the genetically modified trees are planted, all the genetically modified trees there will die, but the non-genetically modified trees will not, probably some of the strong trees will survive. And these genetically modified are having damages in our cities.
In addition, the article gave all the good things of genetically modified, and the lecture gave all the bad things about genetically modified.