Specialty Crop Information
The Specialty Crop Information section of VIP is meant as a general source of information pertaining to climate impacts on various types of vegetation. VIP users are welcome to submit anything they wish to help better communicate these interactions. Please send information to firstname.lastname@example.org.
Courtesy of RaintreeNursery.com
|Apple||400-1000 (low-chill varieties are less)||Peach||600-800|
|Bud Development Stage1||Average Temperature (°F) for2|
|10% kill||90% kill|
|Sweet Cherry (Bing) or Sour Cherry|
Source: Iowa State University Extension
1 For specific bud development state temperature thresholds, please visit the full resource guide from ISU Extension.
2 Under very calm conditions the fruit bud temperature can be lower than the air temperature, resulting in injury when recorded temperatures are slightly above the critical level.
During the growing season, crops have upper and lower development thresholds outside of which they don’t develop physiologically. For example, the upper and lower development thresholds for corn are 86°F (upper) and 50°F (lower). The assumption is that development of corn is limited once the temperature exceeds 86°F or falls below 50°F.
The lower development threshold is also called the “base temperature” or Tbase. These thresholds are used when calculating growing degree days for specific crops. The equation for growing degree days is:
Using the “Degree Day” tool on cli-MATE, the user can specify the base temperature for the growing degree day calculation (Station Data > Daily > Degree Days). For more information on Growing Degree Days, please visit here: http://mrcc.isws.illinois.edu/CLIMATE/Station/Daily/degreeday_description.html
The tables below show the base temperature (Tbase) for many specialty crops, sorted by crop name and by base temperature.
BY CROP NAME
BY BASE TEMP
|40||Asparagus, Barley, Beet, Broccoli, Collards, Flaxseed, Lettuce, Oats, Pea, Potato, Rye, Wheat|
|45||Potato, Squash, Sunflower|
|50||Bean (snap), Corn, Muskmelon, Pepper, Rice, Sorghum, Soybeans, Sweet Corn, Tomato|
|60||Eggplant, Okra, Sweet Potato|
Peter Hirst and Bruce Bordelon, Purdue Extension
Apples and Pears: These fruits are very hardy, but extremely cold temperatures close to -15°F could produce some bud damage.
Peaches and Nectarines: The rule of thumb is that some flower bud kill occurs at -10°F and for every degree below -10°F, 10% of flower buds are lost. At -20°F, expect complete flower bud mortality.
Sweet and tart cherries: Tart cherries are hardier to extreme cold than sweets. However, temperatures around -15°F is when some bud damage could occur in both sweet and tart cherries.
Blueberries: Highbush blueberries are generally tolerant of temperatures down to -15°F, but an extended period of cold will likely lead to some flower bud kill.
Blackberries: Thorny and thornless blackberries are not hardy below -10°F, so below this threshold, there could be considerable damage to vascular tissue in canes and potentially in the buds themselves. In severe cases, all above ground growth could be killed. Blackberries commonly exhibit a delayed winter injury response where the buds may have survived the winter cold and begin to grow in the spring, but the damage to the vascular tissue in the canes results in collapse of the new growth a few days or weeks after the start of growth.
Raspberries: Red and black raspberries are fairly hardy to cold temperatures, but temperatures around or below -15°F could cause some minimal damage to Midwest varieties.
Grapes: Varieties of grapes can vary widely in amount of damage from extreme cold temperatures. Grapes have a compound bud, with primary, secondary and tertiary growing points. The primaries are usually the first to show cold damage. At temperatures around -15°F, it would be expected that hardy hybrid and American varieties would have 0-25% primary bud damage. This percent loss is management since pruning severity can be adjusted to account for those losses. Less hardy hybrids may have 50% or more bud damage at temperatures around -15°F, which could lead to some yield reduction and potential cane and cordon damage. At temperatures around -15°F, cold tender viniferous varieties likely experience considerable damage to buds, canes, and cordons and possible damage to trunks above the snow line.