Central Iowa
Life Member
I have read some articles and talked to a few people about rotating brassicas to prevent disease and insect infestations and thought I would share what I found. As I checked different websites I found little information specifically to our area so I talked to a few people that have used them on the same plot multiple years. I talked to a man in the Albia area that had used the same plot for turnips for three years in a row. This year he noticed insect problems; this was the third consecutive year for turnips in this plot. His plan for the next two years is to rotate out and use legumes in these plots instead. As well as the benefit of rotating, the soil will also benefit from the legumes ability to fix nitrogen. As well most of the articles I read stated that for proper practices you should not keep these plots in the same spot for more than two consecutive years. The University of Delaware recommends not planting the turnips in the same plot for a period of 2-4 years depending on your disease, or insect threats. Here is a link to their information.
Univ of Deleware Rotation Info The article below from Kent Kammermeyer recommends two years. I have heard mixed reviews regarding usage as some say the deer just walk through them and others say they pound them.. The QDMA’s new Quality Food Plots book states in some cases it may take 2-3 years for deer to acquire a taste for them. I have been around them for two years now and have seen heavy usage the first years introduced and strongly recommend them for late season plots as they are very easy to grow.
Here is the article from Kent Kammermeyer from the QDMA.
Now for the part that your mama never told you: Don't plant Brassicas on the same ground for more than two successive years! Not even in the same field, they need to be rotated out due to diseases such as anthracnose, powdery mildew, root knot, leaf spot, white rust, scab, turnip mosaic virus and rhizoctonia rot. The worst of these do not just injure the plant, they can cause an entire crop to turn black and die in a short period of time. The effect is less intense in the north because cold destroys some of the organisms. New Zealand varieties are likely more vulnerable to the funguses than those grown in the US for years.
Some varieties of turnips, canola, and rape have some genetic resistance but none are immune to the disease complex. There is no substitute for crop rotation! Rest the area for a minimum of two years. A clover/wheat mix makes an excellent alternate crop for deer.
Another important reason for crop rotation is that Brassicas are also attacked by insects that quickly build up in successive years such as the cabbage flea beetle, striped flea beetle and the common aphid.
Bottom line: enjoy your Brassica patches while they last, but rotate them out after two years to prevent big trouble. There is no substitute for crop rotation!
Here are the definitions of some of the diseases that were mentioned above.
DISEASES
As for insects, diseases in a field can be detrimental to a market and a food reserve. Scouting is again necessary to determine the areas where disease are prevalent and the control needed as well as, to decrease the number of outbreaks. There are numerous diseases which affect turnips.
Black Rot- caused by Xanthomonas compestris pv. campestris. This disease affects the above ground portion of the crop but may also affect the roots. Roots which are affected are known to develop dry rot, leading to upmost devistation of a crop. Signs of this disease include dwarfing of young seedlings, and lower leaf drop, a V shaped pattern will form on the leaves and as the disease progresses to the to the midrib of the leaf it causes the veins to turn black, thus the infected portion becomes brown and dry. The best means of control is using bacteria free seed. Using seed treated by hot water treatments and spraying the crop with a fungicide at 7-10 day intervals will decrease the possible spread of the disease.
Root Knot Nematodes- Meloidogyne spp. Root knot nematodes invade the root portion of the crop causing infected roots to swell at the invasion point and develop knot gall. Above ground symptoms such as decreasing growth, and wilting yellow leaves. Overall the plant dies prematurely. Chemical treatments with a nematicide fumigant is the best possible means of control.
Clubroot- Plasmodiophora brassicae is one of the most serious soilborne diseases of the Brassica family, especially detrimental in soils which are acidic. As soil temperatures rise the disease becomes more aggressive. Disease offspring known as zoospores enter into the plant by its roots, through either parasitic wounds or mechanical wounds. A club like or knot like structure is formed at the roots where extreme cell malformation has occurred. Symptoms appear as continual wilting and then recovery, eventually the plant does not recover and thus dies. Rotation with nonsucceptible crops, sanitation, and disinfecting equipment, and a pH above 7.3 discourage the disease.
Fusarium Wilt-Fusarium oxysporum F.sp spinaclae is a seedborne and soilborne fungus that is common if soil temperature is warm. The main symptom of the disease is a vascular discoloration in crown area. Other symptoms include pale green and leafy margins, a rolling of leaves inward as the plant then wilts and dies. Treated seed and field rotation are the best methods of control for this disease.
Downy Mildew- Peronospora parasitica Penetrates the vegetative growth between leaf cells as the disease spreads. Disproportionate, purple spots begin developing on leaves, and stems, these enlarging spots becoming yellow brown. A mildew forms and grows under the leaf surface. Overwintering structures can be found on plants or in infected plant debris. Humid coastal regions are a haven for this disease which can cause damage to young plants and transit crops. Extremely moist and temperatures between 50-60 degrees°F can encourage this disease. Crop rotation, and fall plow will decrease incidence.
Black leg- Phoma lingam. Survival is within seed and infected plant debris. Infected seed germinate causing a fungus to grow quickly infecting the seedlings causing lesions, and stunting of overall growth. Rainfall and irrigation can spread the disease from a diseased plant to a healthy plant.
Turnip Yellow Mosaic virus is transmitted by over 50 different species of aphids. Symptoms of this virus include black necrotic spots, leaf distortion, stunting, mosaics, and mottling.
Univ of Deleware Rotation Info The article below from Kent Kammermeyer recommends two years. I have heard mixed reviews regarding usage as some say the deer just walk through them and others say they pound them.. The QDMA’s new Quality Food Plots book states in some cases it may take 2-3 years for deer to acquire a taste for them. I have been around them for two years now and have seen heavy usage the first years introduced and strongly recommend them for late season plots as they are very easy to grow.
Here is the article from Kent Kammermeyer from the QDMA.
Now for the part that your mama never told you: Don't plant Brassicas on the same ground for more than two successive years! Not even in the same field, they need to be rotated out due to diseases such as anthracnose, powdery mildew, root knot, leaf spot, white rust, scab, turnip mosaic virus and rhizoctonia rot. The worst of these do not just injure the plant, they can cause an entire crop to turn black and die in a short period of time. The effect is less intense in the north because cold destroys some of the organisms. New Zealand varieties are likely more vulnerable to the funguses than those grown in the US for years.
Some varieties of turnips, canola, and rape have some genetic resistance but none are immune to the disease complex. There is no substitute for crop rotation! Rest the area for a minimum of two years. A clover/wheat mix makes an excellent alternate crop for deer.
Another important reason for crop rotation is that Brassicas are also attacked by insects that quickly build up in successive years such as the cabbage flea beetle, striped flea beetle and the common aphid.
Bottom line: enjoy your Brassica patches while they last, but rotate them out after two years to prevent big trouble. There is no substitute for crop rotation!
Here are the definitions of some of the diseases that were mentioned above.
DISEASES
As for insects, diseases in a field can be detrimental to a market and a food reserve. Scouting is again necessary to determine the areas where disease are prevalent and the control needed as well as, to decrease the number of outbreaks. There are numerous diseases which affect turnips.
Black Rot- caused by Xanthomonas compestris pv. campestris. This disease affects the above ground portion of the crop but may also affect the roots. Roots which are affected are known to develop dry rot, leading to upmost devistation of a crop. Signs of this disease include dwarfing of young seedlings, and lower leaf drop, a V shaped pattern will form on the leaves and as the disease progresses to the to the midrib of the leaf it causes the veins to turn black, thus the infected portion becomes brown and dry. The best means of control is using bacteria free seed. Using seed treated by hot water treatments and spraying the crop with a fungicide at 7-10 day intervals will decrease the possible spread of the disease.
Root Knot Nematodes- Meloidogyne spp. Root knot nematodes invade the root portion of the crop causing infected roots to swell at the invasion point and develop knot gall. Above ground symptoms such as decreasing growth, and wilting yellow leaves. Overall the plant dies prematurely. Chemical treatments with a nematicide fumigant is the best possible means of control.
Clubroot- Plasmodiophora brassicae is one of the most serious soilborne diseases of the Brassica family, especially detrimental in soils which are acidic. As soil temperatures rise the disease becomes more aggressive. Disease offspring known as zoospores enter into the plant by its roots, through either parasitic wounds or mechanical wounds. A club like or knot like structure is formed at the roots where extreme cell malformation has occurred. Symptoms appear as continual wilting and then recovery, eventually the plant does not recover and thus dies. Rotation with nonsucceptible crops, sanitation, and disinfecting equipment, and a pH above 7.3 discourage the disease.
Fusarium Wilt-Fusarium oxysporum F.sp spinaclae is a seedborne and soilborne fungus that is common if soil temperature is warm. The main symptom of the disease is a vascular discoloration in crown area. Other symptoms include pale green and leafy margins, a rolling of leaves inward as the plant then wilts and dies. Treated seed and field rotation are the best methods of control for this disease.
Downy Mildew- Peronospora parasitica Penetrates the vegetative growth between leaf cells as the disease spreads. Disproportionate, purple spots begin developing on leaves, and stems, these enlarging spots becoming yellow brown. A mildew forms and grows under the leaf surface. Overwintering structures can be found on plants or in infected plant debris. Humid coastal regions are a haven for this disease which can cause damage to young plants and transit crops. Extremely moist and temperatures between 50-60 degrees°F can encourage this disease. Crop rotation, and fall plow will decrease incidence.
Black leg- Phoma lingam. Survival is within seed and infected plant debris. Infected seed germinate causing a fungus to grow quickly infecting the seedlings causing lesions, and stunting of overall growth. Rainfall and irrigation can spread the disease from a diseased plant to a healthy plant.
Turnip Yellow Mosaic virus is transmitted by over 50 different species of aphids. Symptoms of this virus include black necrotic spots, leaf distortion, stunting, mosaics, and mottling.
