Posts Tagged ‘snap bean’

Weed Control for Succulent Beans

Friday, June 22nd, 2012

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

There is some overlap of herbicide options for snap beans and lima beans, but growers need to pay particular attention that a product is labeled for snaps or lima beans and do not assume if it is labeled for one, it is labeled for both. One thing that is consistent for both lima and snap beans is that postemergence herbicides need to be applied to small weed seedlings (3 inches tall or less).

Snap Beans
Weed control in snap beans starts with a good soil-applied program. The regional recommendations include Eptam, Treflan or Prowl, applied pre-plant incorporated; Dual, which can be applied preemergence or pre-plant incorporated; or Command or Sandea applied preemergence. Early postemergence treatments for broadleaf weeds include Basagran, Reflex, or Sandea. Select Max, Targa/Assure II, or Poast are labeled for postemergence grass control. UD research has seen consistent control with Dual used at planting followed by a timely (1 to 2 trifoliate stage of the beans) application of Reflex and Basagran. If there are concerns about timely application of the postemergence herbicides, consider use of a broadleaf weed herbicide at planting.

Lima Beans
The biggest difference from snap bean herbicides is Reflex. Snap beans tolerate Reflex quite well, but lima beans are very sensitive to Reflex. In fact, Reflex applied earlier in the season then lima beans planted as a second crop can also result in lima bean injury. A soil-applied herbicide program for lima beans is very important due to the lack of effective postemergence herbicides. Herbicides listed in the regional vegetable guide for lima beans include:

Pre-plant incorporated: Prowl or Treflan

Pre-plant incorporated or preemergence: Dual or Pursuit

Preemergence only: Sandea or Spartan Charge (only labeled in DE)

Postemergence: Basagran or Raptor for broadleaf weeds; Select Max or Poast for grasses.

Vegetable Disease Update – August 26, 2011

Friday, August 26th, 2011

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

With the impending hurricane we will probably see large amounts of rainfall. For vine crops fields with a history of Phytophthora fruit rot it will mean more Phytophthora fruit rot if any marketable watermelon or cantaloupe remain but it will really threaten the pumpkin crop. No fungicide will protect fruit from fruit rot if we get huge amounts of rainfall. Standing water in the fields will be the biggest indicator of possible fruit rot damage. There would be some benefit to protecting foliage with fungicides before the storm arrives if there is time and there is no history of Phytophthora fruit rot. This would be true for many vegetables including vine crops, tomatoes, and others. If there is no Phytophthora fruit rot present in a pumpkin field, fungicides such as Presidio, Ranman, Revus or Forum plus a fixed copper could be considered to suppress Phytophthora fruit rot, if Phytophthora spores moving in water from other fields should be introduced. Fruit have to be covered for the materials to have a hope of having an effect.

For other vegetables such as tomatoes, peppers and other fruiting vegetables that may be planted for late harvest fungicide applications should be made before the rains arrive not after. Prevention is the key to control. If the label allows, adjuvants that help products adhere to the plants should be considered. Spreader-stickers would be encouraged if the crop and label warrant it.

In crops where cottony leak caused by Pythium could cause crop loss, such as snapbeans and lima beans, application of one of the phosphonate fungicides such as ProPhyt or Phostrol would be suggested at maximum rates, or Ridomil Gold/Copper on snapbeans only. There is a 24c label for Ridomil Gold/Copper (2.0 lbs/A) in DE, MD and VA for cottony leak on snapbeans. Lima bean growers will want to scout carefully once this storm clears out for downy mildew. Wet soil and cool temperatures will favor downy mildew infection.

Cucurbit downy mildew is present on pumpkin now in the sentinel plot in Newark in New Castle County. This is the first report of downy mildew on pumpkin. It has probably been there for several days. Growers should continue to apply fungicides for leaf diseases including downy mildew.

 

Boron Toxicity in Beans

Friday, July 8th, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

We recently had a suspected case of boron toxicity in snap beans. Boron toxicity is common in western states where boron levels in soils or irrigation water are high. In the east, we do not have high boron soils or high levels in irrigation water. In addition, boron leaches readily from soils. Boron toxicities therefore occur only when excess boron is applied in fertilizers.

Boron is a micronutrient needed by plants. It is closely associated with calcium and calcium transport, cell wall production, cell division in plant growing points, sugar transport in plants, flower and fruit development, and plant hormone regulation. Vegetables vary in their boron requirements. Cole crops, turnips, and beets have the highest demands. Even so, recommended rates of application in low boron soils for these high demand crops is only 3 lbs/acre. More commonly, 1-2 lbs of boron per acre is applied to vegetables as a broadcast. Margin of safety for boron application is small and excess application or improper blending in fertilizers may lead to toxicities – deficiencies show up at 1 ppm and toxicities appear at 5 ppm of available boron in the soil.

The vegetable crops most sensitive to excess boron are beans, particularly snap beans. Boron is generally not recommended for snap bean production and boron should never be included in starter fertilizer for snap beans. Boron toxicity often occurs where starter fertilizer containing boron for other crops, such as corn, is applied to snap beans.

Boron toxicity in beans commonly appears as yellowing in unifoliate leaves with burning of leaf edges and yellowing of leaf edges of the older trifoliate leaves that can progress to edge burn. In severe cases, plants will develop a scorched appearance and leaves may prematurely drop off.

 

Physiological Leaf Cupping and Rolling in Vegetables

Friday, July 1st, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Leaf cupping and rolling in vegetables can be caused by virus diseases, aphid infestations, herbicides and growth regulators. However, late spring and early summer is the time of the year that we often see leaf cupping and rolling disorders appear in vegetable crops that are not related to pests or chemicals. This can be seen in tomatoes, peppers, potatoes, watermelons, beans, and other crops. This is a physiological disorder that may have many contributing factors.

In tomatoes, leaf roll starts at the margins which turn up, then roll inward, most commonly on the lower leaves. Upward cupping is also found commonly in watermelons and potatoes. Beans, peppers, and other vegetables may cup downwards. Leaves may stay in this rolled or cupped state for a short period of time and then return to normal, or they may remain permanently rolled or cupped. Rolled leaves may become thicker but are otherwise normal. Physiological leaf roll or cupping is often variety dependent with some varieties being more susceptible than others.

There are several possible causal factors for physiological leaf roll or cupping. Water relations are suspected in many cases where there has been a reduction in water uptake or increased water demand placed on the plant. The plant responds by rolling the leaves which reduces the surface area exposed to high radiation. High temperatures, excessive pruning, cultivation, and vine moving activities may also trigger leaf rolling. High nitrogen fertility programs followed by moisture stress may also trigger this type of leaf roll. Inadequate calcium moving to leaf margins may also cause a different type of leaf cupping. This is also related to interrupted water movement.

In most cases, yields are not affected by physiological leaf rolling or cupping. However, growers may choose to select varieties that are less susceptible to this disorder.

 

Air Pollution in Vegetables

Friday, June 24th, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

We are starting to see evidence of air pollution damage in sensitive vegetable plants. Those vegetables most susceptible include potatoes, watermelons, cantaloupes, snap beans, pumpkins, and squash.

Damage is most common during hot, humid, hazy weather with little wind. Air inversions, when warm air at the surface is trapped by even hotter air in the atmosphere above, lead to build up of air pollutants that cannot disperse and, consequently, plant injury. The most common form of air pollution injury to plants is ozone damage. Ozone is a strong oxidant and is formed by the action of sunlight on products of fuel combustion. It is moved from areas of high concentration (cities, heavy traffic areas) to nearby fields.

Ozone injury in susceptible vegetable varieties develops when ozone levels are over 80 ppb for four or five consecutive hours, or 70 ppb for a day or two when vegetable foliage at a susceptible stage of growth. Because it occurs in areas with high levels of automobile exhausts, crop injury is often visible on fields in close proximity to roads, especially with heavy summer weekend traffic. High pollution indexes in Baltimore and Washington are also a good indication that ozone damage may occur.

In potatoes, symptoms of ozone damage occur on the most recently emerged leaves and can be seen as a black flecking. Early red varieties are most susceptible.

Injury on watermelon leaves consists of premature chlorosis (yellowing) on older leaves. Leaves subsequently develop brown or black spots with white patches. Watermelons are generally more susceptible than other cucurbits to ozone damage. Damage is more prevalent when fruits are maturing or when plants are under stress. Injury is seen on crown leaves first and then progresses outward. Seedless watermelon varieties tend to be more resistant to air pollution injury than seeded varieties, so injury often shows up on the pollenizer plants first. “Ice box” types are the most susceptible.

Ozone injury on watermelon

In muskmelons and other melons, the upper surface of leaves goes directly from yellow to a bleached white appearance.

Ozone injury on squash and pumpkins is intermediate between watermelon and cantaloupe starting with yellowing of older interior or crown leaves. These leaves subsequently turn a bleached white color with veins often remaining green.

In snap and lima beans, ozone causes small bleached spots giving a bronze appearance on upper leaf surfaces and pods. Leaves may ultimately turn chlorotic and senesce (drop).

Ozone injury can be easily misdiagnosed as mite injury, pesticide phytotoxicity, or deficiencies.

The key to avoiding air pollution injury is to plant varieties that are of low susceptibility and to limit plant stresses. Certain fungicides such as thiophanate methyl (Topsin and others) offer some protection against ozone damage.

 

September Vegetable Observations

Friday, September 10th, 2010

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Lima Beans
Lima bean harvest is fully underway across the region and the following are some observations in this challenging year. Late May, June, and some early July plantings lost the first set almost completely (heat induced blossom and small pod abortions). The second set is extremely variable and in many fields, economic yields will depend on what happens with the third set. Growers have commented that they are letting fields advance well above the 10% white/dry seed level that is normal for harvest to allow the later set to fill. Some fields are being harvested at the 20-30% dry seed stage (coming from the earlier set). For harvest considerations, it is better to lose a set completely and harvest the later set than to have a bad split set.

There is still considerable dry land lima bean acreage and I am always amazed at how much drought that lima beans can stand without wilting or showing outward water stress. Plants may be smaller but they survive drought and heat very well. Unfortunately, even though lima beans can survive drought, pod set will be limited. Research has shown over and over again that irrigation is necessary to achieve high lima bean yields. In a year such as 2010 where excess heat is also an issue, pod set can be adversely affected, even under irrigation.

We should emphasize again that water is still the most important nutrient for high lima bean yields. In a research plot area where we were looking at residual effects of biofumigant crops and compost this year, we planted snap beans and lima beans in early June as test crops in a dry land situation. After several weeks of drought and heat the snap beans were wilting during the day and were stunted while the lima beans kept on going. To rescue the plots (so that we could get data), we installed drip irrigation between every 2 rows. The snap beans did recover somewhat but with permanently stunted plants, poor bean quality, and a severe split set. In contrast, the lima beans lost the first set but did put on a decent second set and had good plant health and plant size.

Snap Beans
Summer planted snap beans for September harvest are yielding much better than the summer harvested crops. We are seeing yields in the normal 4 ton/A or better range where there was adequate irrigation (compared to summer yields in the 1-2 ton range).

Pickle Cucumbers
Late crops of pickle cucumbers are variable, largely due to stand loss and inadequate water in fields planted during summer high heat periods. In addition, downy mildew has hit a number of later fields adversely, even where fungicides were applied in a timely manner. Pickle harvest should be completed in the next 7-10 days.

Watermelons
I am amazed at how long some watermelon fields have produced this year where attention has been paid to vine health, nutrition, and water. This certainly is the year where you are able to evaluate the yield potential and longevity of main season varieties and effectiveness of pollenizers. On another note, watermelon fields with good weed control (morningglory in particular), had much better later yields.

Tomatoes
Tomatoes had a difficult year in 2010 with most fields having much shorter harvest periods due to the extra heat stress. This is especially evident where beds were allowed to dry out at any time during these stressful periods. Somewhat surprising also is the presence of more disease than would be expected in a dry year.

Vegetable Disease Update – July 2, 2010

Friday, July 2nd, 2010

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

Cucurbit Downy Mildew
We are at minimal risk at the present but keep up to date by checking the ipm PIPE website http://cdm.ipmpipe.org regularly for updates. Downy mildew was found in New York state for the first time on cucumber in Erie and Niagara counties close to the Ontario, Canada infection site. The northern march of downy has been slowed. We have had some weather patterns coming north but the clear skies and plenty of UV radiation have probably been keeping viable spore number low. We are checking our sentinel plots weekly for downy mildew here in DE.

Bacterial Wilt
Bacterial wilt on slicing cucumbers was diagnosed this week. Symptoms on this planting were random wilting of several runners on 20% of the plants. Sticky strands of bacterial ooze can be seen when the cut ends of the wilted runners are touched together then slowly drawn apart. Striped and spotted cucumber beetles carry the bacteria on their mouthparts and inoculate them when they feed on the succulent stems early in the season. Bacterial wilt is not seed borne and does not persist in the soil more than 2-3 months. It is thought that the bacteria acquire the bacteria from infected weed or volunteer cucurbit hosts. Cucumber beetle control is the primary control method.

Strands of bacterial ooze from touching cut ends of infected runner and pulling them apart slowly

Potato and Tomato Late Blight Webinar for Home Gardeners
Rutgers, Penn State and Cornell University vegetable plant pathologists will be holding a Webinar on Potato and Tomato Late Blight for home gardeners on July 13, 2010 at 6:30 PM. You are encouraged to participate in this timely topic. The linked announcement has all the information to enroll. It will be a good review for commercial producers as well.

Pythium Blight or Cottony Leak on Snap Beans
Pythium blight or cottony leak on snap beans was diagnosed early this week. This disease likes the hot, humid conditions that we had before this recent break in the weather. When we go back to the humid weather again with scattered showers and irrigation this disease can be a threat. Look for the cottony white growth in the lower canopy and on pods close to the ground. There is a 24c registration for Ridomil Gold Copper (2 lbs/A) for prevention of Pythium blight in DE, MD and VA. Several applications may be necessary if favorable weather persists.

Cucurbit Powdery Mildew
Powdery mildew on cucurbits has been reported in New Jersey. Delaware growers should be scouting and begin applying fungicides for powdery mildew once 1 old leaf in 45 has been found with powdery mildew. See the article titled Powdery Mildew on Cucurbits in WCU 18:15 for suggested fungicides.

Mocap EC 24c Label for Limas and Snap Beans Withdrawn

Thursday, May 20th, 2010

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

Mocap EC section 24c special local need label for lima and snapbeans in DE was withdrawn by Bayer Crop Science after EPA determined that human health risk findings required reduced application rates. The recommended reduced rate can offer control on garden symphylans, but can only provide suppression to nematodes. Since root knot and other nematodes will not be controlled the label was withdrawn. This does not affect the use of Mocap 10G, if growers have granular applicator boxes for their planters this formulation is effective at the label rates.

Weed Control in Succulent Beans

Thursday, April 22nd, 2010

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

There is some overlap of herbicide options for snap beans and lima beans, but you need to pay particular attention that a product is labeled for snaps or lima beans and do not assume if it is labeled for one, it is labeled for both.

Snap Beans
Weed control in snap beans starts with a good soil-applied program. The regional recommendations include Eptam, Treflan or Prowl applied pre-plant incorporated; Dual, which can be applied preemergence or pre-plant incorporated; or Command or Sandea applied preemergence. Early postemergence treatments for broadleaf weeds include Basagran, Reflex, or Sandea. Select Max, Targa/Assure II, or Poast are labeled for postemergence grass control. UD research has seen consistent control with Dual used at planting followed by a timely (1 to 2 trifoliate stage of the beans) application of Reflex and Basagran. If there are concerns about timely application of the postemergence herbicides, consider use of a broadleaf weed herbicide at planting.

Lima Beans
The biggest difference from snap bean herbicides is that Reflex cannot be used for lima beans since they are very sensitive to Reflex and severe injury will occur. A soil-applied herbicide program for lima beans is very important due to the lack of effective postemergence herbicides. Herbicides listed in the regional vegetable guide for lima beans include:

Pre-plant incorporated: Prowl or Treflan
Pre-plant incorporated or preemergence: Dual or Pursuit
Preemergence only: Sandea
Postemergence: Basagran or Raptor for broadleaf weeds; Select Max or Poast for grasses.

Soybean Cyst Nematode Diagnosed in Soybean and Snap Bean

Thursday, July 2nd, 2009

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

SCN was diagnosed this past week in soybeans and snapbeans. These two hosts are the only crops that are affected in the region. If you see stunting and yellowing, carefully dig up the affected plants with a shovel or trowel and gently shake the soil from the roots. White or yellow females will be seen attached to the infected roots if present. They are small, much smaller than the nitrogen fixing nodules, but can be seen with the naked eye. A 10x hand lens makes the task much easier to see the lemon shaped females. Don’t presume that all the stunting that can be seen is due to water-logged soils or compaction. If it is not clear what the problem is or if cysts cannot be seen, a soil sample of the affected area can be taken and checked for SCN or other nematodes. Test bags and more information is available at the County Extension offices and forms and info at the Plant Diagnostic Lab site at http://ag.udel.edu/extension/pdc/pdf/Nematode_Assay_taking_samples.pdf.

soybean cyst nematode