Whether or not you pay the farmer to take care of your plants, they may suffer a disease tick which makes them take longer to grow. That is a correct statement.
However, when the only patches that do not update or have not updated 24 hours after you planted them are the fruit tree patches with the exception of the Tree Gnome Stronghold patch that is a bug. You should file a bug report. When that happens over and over again exactly the same way, that is a highly annoying bug.
So if you take the old grow times as a guideline, that means that the disease ticks happened over every single tick for at about 10 hours and only on the tree patches other than the Tree Gnome Stronghold one which never seems to have them and is always full grown the next day if I replanted it the day before.
May all fan boys/girls die when Runescape does since they can't seem to live without it.
Now Goodbye and Good riddance.