Although punctuation is largely a matter of writing style, at some point it is also a matter of structural logic. If we reworked your original list as a straightforward run-together sentence, it might look like this:
These are my favorite fruits: apples, bananas, kiwis, tomatoes, pineapples, watermelons, and oranges.
Or it might look like this:
These are my favorite fruits: apples; bananas; kiwis; tomatoes; pineapples; watermelons; and oranges.
(Many writers, editors, and readers would say that using semicolons in a simple list like this one is overkill, since commas can handle the job quite satisfactorily, but that doesn't mean that using semicolons is irrational or otherwise indefensible.)
But it would be illogical for it to look like this:
These are my favorite fruits: apples, bananas, kiwis, tomatoes, pineapples, watermelons, and; oranges.
It would be illogical because putting a semicolon—or a comma—after and between the next-to-last and last entries in a series serves no useful purpose and, in fact, is counterproductive because it temporarily brings readers to a standstill at a point where they should be moving freely to the final element in the series.
Style guide advice on how to punctuate vertical (or displayed) lists
When writers break out the elements of an extended list into a bulleted, numbered, or unnumbered vertical (or displayed) list—rather than running it in as regular text—they don't have any reason to add punctuation that wouldn't be in the run-in version. To the contrary, breaking out each element offers the opportunity to remove punctuation that the vertical presentation renders unnecessary.
Most style guides that discuss punctuation of vertical lists distinguish between lists whose elements consist of complete sentences and lists whose elements do not. In the former case, the elements receive the same end punctuation that they would if they were appearing in regular running text; in the the latter case, the elements receive no end punctuation.
Here, for example, is how The Chicago Manual of Style, sixteenth edition (2010) handles this question:
6.124 Vertical lists—punctuation and format. A vertical list is best introduced by a complete grammatical sentence, followed by a colon (but see 6.125 [which discusses how to punctuate vertical lists whose elements complete a fragmentary sentence begun in the introduction to the list]). Items carry no closing punctuation unless they consist of complete sentences. [Example:]
Your application must include the following documents:
- a full résumé
- three letters of recommendation
- all your diplomas, from high school to graduate school
- a brief essay indicating why you want the position and why you consider yourself qualified for it
- two forms of identification
Notice that there is no punctuation at the end of each of the parallel elements in the list and that there is no and at the end of the next-to-last element.
The Oxford Guide to Style (2003) offers similar guidelines:
9.1.4 Displayed lists ... List items that are complete sentences start with capitals and end in full points, regardless of the length of the sentence or number of subheadings. Sentence fragments do not, and are usually (but not exclusively) lowercase.
Lists—particularly short lists where each element is a sentence or less—may use a typographical symbol such as a bullet ... in place of numbers. This device is useful for arranging displayed items without imposing an artificial hierarchy upon them. Here are two examples of unordered lists:
- The battlements or crenellation (der Zinnenkranz)
- The tower platform (die Wehrplatte)
- The merlon (die Zinne)
- The inner ward or battery (der Burghof)
- The draw-well (der Ziehbrunnen)
- The keep or donjon (der Burgfried)
- The dungeon (das Verlies)
Applying the preceding style guide advice to the OP's sentence
It seems clear to me that both Chicago and Oxford would endorse the following treatment of the list sentence that appears in the posted question, assuming that they would approve of presenting so simple a series of elements as the fruits in the original list in a display format:
These are my favorite fruits:
They might disagree about whether to capitalize the first letter in each bulleted entry, but they are in complete harmony about removing any punctuation at the end of each entry and removing the and in the penultimate entry.