The term "brassica" covers a large group of plants that include radishes, turnips, rutabagas, cabbages, cauliflower, canola, rape and kale. However, when deer managers talk about brassicas they are usually referring to kale, rape and turnips, as these are the most common species of brassicas planted in deer food plots. The remainder of this section will focus specifically on these three species.
General characteristics of brassicas
As a group, the brassicas are cool-season annuals that are high in protein and highly digestible. Protein content ranges from 15% to 20% in the leaves and from 8% to 15% in the roots. The leaves are over 90% digestible. Well-maintained brassica plots are highly productive and can produce 8 or more tons of forage per acre. This high production makes brassicas suitable for planting on small acreage food plots.
Brassica quality increases with maturity
Unlike other forage crops that become fibrous when they mature, the fiber content of brassica leaves doesn't increase with age. This means that the leaves remain very digestible to deer throughout the growing season. However, when brassicas are young the leaves tend to be bitter, so deer rarely eat young plants. Once the plants reach maturity, starches in the leaves are converted into sugars which makes the leaves sweeter and very palatable to deer. The amount of time required for plants to reach maturity depends mostly on the species and variety of brassica you plant. However, brassicas grown on soils with pH close to 6.8 tend to reach maturity faster than plants grown on more acidic soils. Also, the sweetening process is sped up by the first hard frost.
Brassica use by deer
It is not uncommon to have a brassica plot go completely unused by deer throughout most of the growing season. Deer tend to be attracted to brassica plots after the first hard frost makes the plants sweet and palatable. Most brassicas remain upright during cold weather and they will remain green below the snow. It is not uncommon for deer to dig through the snow to feed on brassicas into early March. As a result, brassicas are especially valuable as a late-fall through mid-winter food source, and they are ideal for planting in plots you want to hunt over.
Soil requirements of brassicas
Brassicas grow best when they are planted in well drained soils with pH as close to 6.8 as possible. They will tolerate pH as low as 5.5. You can plant each variety of brassica alone, but it is generally better to plant a plot with two or three species or varieties that will mature at different times. This will extend the amount of time that your plot is nutritious and attractive to deer.
Planting brassicas with other forages
Brassicas can be planted in combination with other forages such as clovers and chicory. However, because brassicas are large plants with big leaves they can easily shade-out other forages. Therefore, you need to be careful about seeding rates. If planting brassicas with clover and chicory, keep the brassica portion of the seed mix to no more than 2 lbs/acre. If you have the room, it is advisable to divide your food plot into sections and plant some parts of the plot with a mixture of brassicas, and the other parts with clover and chicory. For example, you might plant half of the plot in brassicas and half of the plot in the clover chicory mix.
Disease concerns with brassicas
Some references suggest that brassicas can be susceptible to root and leaf diseases if brassicas are planted in the same plot for more than two consecutive years. Seed companies are working to develop brassica varieties that are resistant to these types of diseases. If you have a number of food plots, it is advisable to rotate your brassica plantings between them every couple of years.
Types of brassicas
The following is a description of the three most common brassica species planted in deer food plots.
Forage rape is a brassica that grows very quickly, and depending on the variety, will reach maturity in 30 to 90 days. It is tolerant of cold, drought and heat. Therefore, it can be grown throughout the country and into southern Canada. Deer eat the leaves.
Planting dates for forage rape
Forage rape can be planted in early spring if you want the plants to mature and be attractive to deer between August through September. If you want deer to use the food plots in late October through mid winter, plant forage rape in mid- to late-July. If you are planting in northern regions be sure to plant no later than late June to assure that plants have time to reach maximum production before the first hard frost.
Varieties of forage rape
Forage rape is available in dwarf types and tall types. Dwarf types are probably the best choice for deer food plots as these varieties mature quicker than tall types and are less susceptible to overgrazing. Dwarf Essex is the most commonly available variety of forage rape. Mairaki is a variety that becomes palatable early in its growth. Bioroa is a fast-growing forage rape that is especially resistant to drought. Oamaru produces a large amount of forage and it is slow to mature, so it provides a good late-season food source. Other varieties of forage rape include Winfred and UpSurgeTM.
Kale is a brassica that is slower growing and less tolerant of heat than forage rape. It tends to grow best in regions where the summers are cool. It produces a large amount of forage so it is especially valuable if you want to provide deer with an abundant high-quality food source in late-fall through mid-winter. Deer eat the leaves.
Stemmed and stemless kale
Kale is available in stemmed and stemless varieties. Stemless varieties establish quicker than those with stems and they mature in about 90 days. Stemmed varieties require between 150 to 180 days to reach maximum production.
Planting dates for kale
Plant stemless kale in early spring if you want plants to mature in August through September. Plant stemmed kale in early spring if you want plants to mature in late October through mid-winter.
Varieties of kale
Varieties of kale include Blue Ridge, Darkibor, Dwarf Curled Scotch, Dwarf Green Curled, Dwarf Siberian, Premier, Improved Vates, Redbor, Starbor, Tall Scotch, Vates, Vates Blue Curled, Vates Dwarf Blue, and Siberian.
Turnips are a brassica that grow very quickly and reach their peak production in 80 to 90 days. They will grow in a variety of soil conditions and they grow well in cool northern regions. Deer eat the leaves first and will eat the roots once the leaves are gone
Planting dates for turnips
They are often planted in late summer to provide a late-fall through mid-winter food source to deer.
Varieties of turnips
Different turnip hybrids produce different proportions of leaves to roots. Some varieties produce very few leaves and large roots (15% leaves to 85% roots), while in other varieties over 90% of the production is in leaves. Choose varieties that produce a high proportion of leaves because the leaves are the most nutritious part of the plant. Varieties such as Savannah and All Top produce a greater proportion of leaves to roots. Manaroa is a variety that becomes palatable early in its growth.
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