Follow these procedures for sampling specific fruits, vegetables and trees.
Crop | Stage of growth sampled | Plant part or leaves to sample | Approximate number |
Apples | July 15 to Aug. 15 | Leaf from middle of current terminal shoot | 60 |
Asparagus | Mature fern (August) | Fern from 17 to 35 inches up | 20 |
Beans, snap | Initial flowering | Young mature trifoliate | 50 |
Beans, table | Mature | Young mature leaf | 20 |
Blueberries | First week of harvest | Young mature leaf | 50 |
Broccoli | Heading | Young mature leaf | 15 |
Cabbage | Heads, 1/2 grown | Young wrapper leaf | 15 |
Cantaloupe | Early fruiting | Fifth leaf from tip | 25 |
Carrots | Midgrowth | Young mature leaf | 25 |
Cauliflower | Buttoning | Young mature leaf | 15 |
Celery | Half-grown | Young mature leaf | 20 |
Cherry | Summer | Mature leaves from new growth | 50 |
Cucumbers | Early fruiting | Fifth leaf from tip | 20 |
Grapes | Veraison | Petiole from young mature leaf on shoot (one petiole per shoot) | 60 |
Lettuce | Heads, 1/2 size | Wrapper leaf | 20 |
Onions | Midgrowth | Top, no white portions | 25 |
Peaches and nectarines | Spring at fruit set | Midshoot leaf | 20 |
Peas | First bloom | Recently matured leaflet | 50 |
Pecan | 56-84 days after terminal bud set | leaflet pairs from new growth | 25 |
Peppers | Early fruiting | Young mature leaf | 20 |
Plum | Summer | Whole leaf from midshoot growth | 25 |
Potatoes | 40 to 50 days after emergence | Young mature leaf | 20 |
Pumpkin and squash | Early fruiting | Young mature leaf | 15 |
Radishes | Midgrowth to harvest | Young mature leaf | 40 |
Raspberries | First week in August | Leaf 18'' from tip | 50 |
Spinach | 30 to 50 days old | Young mature leaf | 35 |
Strawberries | At flowering | Young mature leaf | 20 |
Sweet corn | Tasseling to silk | Ear leaf | 10 |
Tomatoes | First mature fruit | Young mature leaf | 20 |
Walnut, black | Summer | Mature leaf from new growth | 5 |
Walnut, English | Summer | Center leaflet from mature leaf | 25 |
Watermelons | Midgrowth | Young mature leaf | 15 |