The mishna[1] discusses an etrog upon which a chazazit (a blister-type formation, which is uncommon in our times) appears. The mishna states that a chazazit disqualifies the etrog only if it covers the majority of the etrog. However, the gemara[2] says that a chazazit can disqualify an etrog even if it is only on a minority of the skin when: 1) the blemishes are in a few places, making the etrog look spotted; or 2) the blemish (of any size) is on the chotem (literally, the nose; see below).
When a blemish has a serious visual impact, the etrog is not considered hadar[3] (pleasing to the eye), which is the word the Torah[4] uses to describe an etrog. If the blemish is located on the top part of the etrog or if it is spread out like a leopard’s spots, the etrog fails the “hadar test.” A major question is whether blemishes (or other cases of lack of hadar) disqualify the etrog only on the first day of Sukkot, when the mitzva is of Torah origin,[5] or even throughout the seven days of Sukkot.[6]
The Rishonim extended the laws that we find regarding chazazit to other changes of color and visible form, such as when part of the etrog is black or white[7] or very dry (according to most opinions).[8] Black spots can come from different sources, but one should assume that any black spot that does not come off with rubbing is problematic.[9] (If one tries to remove such a spot, one should be careful not to rub off some of the skin of the etrog itself in the process.) However, spots that are too small to be noticed through looking casually do not count.[10]
Another common situation is bletlach (scab-like formations, which occur at spots of the etrog that a leaf was touching while the etrog was growing). There is no consensus among poskim regarding whether bletlach are considered blemishes if they protrude from the etrog’s surrounding skin.[11] It is possible that since bletlach are common parts of the normal growth of an etrog, they are not considered blemishes, but rather part of the normal appearance of an etrog.[12] Similarly, the normal appearance of an etrog is yellow. However, although a dark green color disqualifies an etrog,[13] there may be green spots in sensitive areas if they have started to turn yellowish, and this is acceptable.[14]
Where is the chotem, in which small blemishes are a special problem? There are four opinions among the Rishonim,[15] three of which are identified in the sketch below. Some say that it is the area above the etrog’s widest spot. The accepted opinion is that it is where the etrog starts angling toward its point at the pitum (#1).[16] The Bi’ur Halacha[17] writes that all agree that the chotem can begin only in the top half of the etrog.
Most authorities maintain that the disqualification based on multiple blemishes applies only if the total area in which the blemishes appear (measured by encircling them) covers the majority of the etrog. According to most authorities,[18] this disqualification applies even if these blemishes cover a majority of only the width of the etrog and do not cover a majority of the entire surface area.[19]