| 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 |
Flowering | Petiole from young mature leaf |
75 |
| 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 |