Using Google Ngram Viewer and the search terms the fruit are,the fruit is,the fruits are,and then chosing the first quote, taken from a recently published book by a native speaking author, we have

1. The Woody Plant Seed Manual - Page 473

United States. Forest Service, ‎F. T. Bonner, ‎Robert P. Karrfalt - 2008 Found inside – Page 473

The fruits are juicy , 1- to 10 - seeded berries with enlarged , persistent calyxes at the base ( LHBH 1976 ).

2. United States Plant Patents - Page 18 United States. Patent and Trademark Office - 2008

The size of the fruit is large or similar to the size of the fruit of Mutzu. The ratio of height ..

3. The Encyclopedia of Fruit and Nuts - 2008 edited by Jules Janick, Robert E. Paull Found inside – Page 161 Very commonly, the fruit are covered with a waxy bloom.

The inescapable conclusion is that all are correct in context.

[20200924 - Example at 3. replaced by an example to include "fruit are"]

Using Google Ngram Viewer and the search terms the fruit are,the fruit is,the fruits are, and then choosing the first quote, taken from a recently published book by a native speaking author, we have

1. The Woody Plant Seed Manual - Page 473

United States. Forest Service, ‎F. T. Bonner, ‎Robert P. Karrfalt - 2008 Found inside – Page 473

The fruits are juicy , 1- to 10 - seeded berries with enlarged , persistent calyxes at the base ( LHBH 1976 ).

2. United States Plant Patents - Page 18 United States. Patent and Trademark Office - 2008

The size of the fruit is large or similar to the size of the fruit of Mutzu. The ratio of height ..

3. The Encyclopedia of Fruit and Nuts - 2008 edited by Jules Janick, Robert E. Paull Found inside – Page 161 Very commonly, the fruit are covered with a waxy bloom.

The inescapable conclusion is that all are correct in context.

[20200924 - Example at 3. replaced by an example to include "fruit are"]

Using Google Ngram Viewer and the search terms the fruit are,the fruit is,the fruits are,and then chosing the first quote, taken from a recently published book by a native speaking author, we have

1. The Woody Plant Seed Manual - Page 473

United States. Forest Service, ‎F. T. Bonner, ‎Robert P. Karrfalt - 2008 Found inside – Page 473

The fruits are juicy , 1- to 10 - seeded berries with enlarged , persistent calyxes at the base ( LHBH 1976 ).

2. United States Plant Patents - Page 18 United States. Patent and Trademark Office - 2008

The size of the fruit is large or similar to the size of the fruit of Mutzu. The ratio of height ..

3. Commercial Fruit Processing - Page 112 - Jasper Woodroof - 2012 Found inside – Page 112

In this size-grading operation, the fruit is graded into five sizes, three of which are for grade pack,

The inescapable conclusion is that all are correct in context.

Using Google Ngram Viewer and the search terms the fruit are,the fruit is,the fruits are,and then chosing the first quote, taken from a recently published book by a native speaking author, we have

1. The Woody Plant Seed Manual - Page 473

United States. Forest Service, ‎F. T. Bonner, ‎Robert P. Karrfalt - 2008 Found inside – Page 473

The fruits are juicy , 1- to 10 - seeded berries with enlarged , persistent calyxes at the base ( LHBH 1976 ).

2. United States Plant Patents - Page 18 United States. Patent and Trademark Office - 2008

The size of the fruit is large or similar to the size of the fruit of Mutzu. The ratio of height ..

3. The Encyclopedia of Fruit and Nuts - 2008 edited by Jules Janick, Robert E. Paull Found inside – Page 161 Very commonly, the fruit are covered with a waxy bloom.

The inescapable conclusion is that all are correct in context.

[20200924 - Example at 3. replaced by an example to include "fruit are"]