Month: August 2019

Tips for a Successful Zucchini, Squash and Cucumber Harvest

Tim McDermott, OSU Extension Educator- Franklin County ,Previously posted on VegNet Newsletter

For many backyard growers, community gardeners and urban farmers, growing the cucurbits can be a challenge.  This vegetable (fruit?)  family is affected by a large number of garden insects as well as both bacterial and fungal disease.  There are a few tips and tricks that can be used to make sure some harvest makes it to the table or sales booth in 2019.

First thing to do is mind your pollinators.  Cucurbits are commonly dependent on pollinators as they have separate male and female flowers.  Once the flowers emerge, use of pesticides can damage pollinators and lead to decreased harvest.

The male flower is at the bottom right. It is simply a flower at the end of the stem. The female flower of this yellow summer squash is behind the male flower and has an immature fruit at the base.

Scouting is a very important part of the Integrated Pest Management strategy.  I had not seen cucumber beetles in large numbers until the July 4th holiday weekend.  Then I started to see them in moderate to large numbers on my summer squash in central Ohio.

 

Adult Striped Cucumber Beetle. This bug will damage leaves, stems, flowers, and fruit while feeding. It also transmits a bacterial wilt that can rapidly cause death in cucurbit plants.

 

 

This is an adult squash vine borer. They lay eggs at the base of the stems and their larvae then tunnel through the stem of the plant disrupting vascular flow and often killing the plant.

 

 

 

 

 

 

 

 

 

 

These plantings of winter squash, both Waltham Butternut and Buttercup, died over the last weekend in July while the summer squash persisted. Suspects include squash vine borer damage or bacterial wilt from cucumber beetles.

 

Squash bugs are another common pest of cucurbits that can be present in large numbers in plantings.

Squash bug eggs are laid white, then rapidly change color to bronze. They are commonly found on the underside of cucurbit leaves and should be removed immediately when discovered and discarded away from the plants.

This is the juvenile form of squash bugs. They can achieve large numbers fairly rapidly.

Hoof Care—Treatment and Prevention

Susan Schoenian, Sheep & Goat Specialist, University of Maryland Small Ruminant Extension Program
(Previously shared on Premier1Supplies Sheep Guide)

Hoof care is an important aspect of sheep production and management. Hoof diseases can affect the health and welfare of sheep and have a negative effect on productivity. Hooves should be regularly checked for disease and excess growth. Animals which have excessive hoof growth, recurrent hoof problems and/or fail to respond to treatment should be culled.

Continue reading →

Corn Growth & Development – R1 Silking

Today managing your corn crop requires knowledge of the different growth stages of the corn plant.  Growth stage identification is critical for scouting and proper timing of fertilizer and pesticide applications.  Throughout the growing season I will discuss the various corn growth stages and management issue at each stage. 

 

R1 – Silking

Plants defined as Rl must have one or more silks extending outside the husk leaves.  This occurs about 55 to 66 days after emergence. Silks grow about 1 to 1.5 inches per day. Plants are at maximum or near maximum height and have near maximum vegetative dry matter.  Silking (Rl) is the only reproductive stage defined not on the characteristics of individual kernels. Determining the reproductive stage of the crop at and after Rl is based solely on the development of the primary ear.

The silking period is the most sensitive period for the crop; stress at this time can reduce kernel number per ear. Silks on the primary ear must be present while pollen shed occurs for successful pollination and fertilization. Synchronization between pollen shed and silking is important for obtaining high grain yields.

During Rl, both pollination and fertilization occur. Each silk is attached to one potential kernel. A pollen grain can land anywhere on an exposed silk and may germinate leading to fertilization. Silks remain receptive to pollen for a minimum of five days after they emerge.  The first silks to emerge from the husk leaves are those attached to potential kernels near the base (butt) of the ear. Silks attached to potential kernels at the ear tip are last to emerge and may not be pollinated if pollen shed has ended. Some potential kernels will simply not develop into harvestable kernels due to a failure in pollination or fertilization; these kernels will be visible on the ear as small, undeveloped white mounds.  As the plant approaches R2, kernels expand and have angled sides and a flatter top.

At Rl, the ear is at the beginning of a rapid elongation period and is only 40 to 45% of its final length.  Potassium uptake is essentially complete and nitrogen and phosphorus uptake is rapid in the plant. Nutrient content by leaf analysis is highly related to the final grain yield at this time. A response to previously applied fertilizer can be seen.

Management/Scouting: Scout for drought symptoms, Insects: Corn Earworm, Corn Rootworm adults,  and Japanese Beetles Diseases: Eyespot, Gray Leaf Spot, Norther Leaf Blight, Southern Leaf Blight and Tar Spot

 

Drought and Heat Stress

Source: Dr. Peter Thomison

Drought stressed corn near tassel emergence

One of the corn production scenarios agronomists least like is an exceptionally wet spring followed by a hotter and drier than normal July and August. The spring of 2019 was one the wettest on records throughout much of the state and now, as the dry weather that started in July persists, such a scenario seems to be a possibility in many Ohio corn fields. A combination of warm temperatures and inadequate rainfall is beginning to stress corn fields across Ohio. What’s exacerbating this problem are the marginal roots evident in some corn fields. Several factors, including poor planting conditions, surface/sidewall compaction and/or excessively wet soil conditions in June have inhibited good root development in many fields. With the onset of drier, warmer conditions in July, these small, shallow root systems have been unable to extract water deeper in the soil profile. Cooler weather and the possibility of storms later in the week may ease drought stress, which is important because many late planted corn fields (planted throughout June) are near or entering the pollination period, the stage of development most susceptible to drought. Other fields past pollination are vulnerable to kernel abortion, which drought conditions increase.

Corn is at many different stages of development because of the wide range in planting dates. To estimate the impact of dry hot weather on corn yield potential, let us review the effects of moisture deficits on corn growth and development from the late vegetative stages, prior to pollination, to the dent stage of kernel development. Yield losses to moisture stress can be directly related to the number of days that the crop shows stress symptoms during different growth periods. The following summarizes findings of past Iowa work that shows the potential impact of water stress on yield potential. Continue reading →

No Pigweed Left Behind – Late-Season Scouting for Palmer Amaranth and Waterhemp

Source: Dr. Mark Loux (edited)

Remain vigilant!  We have Palmer and Waterhemp in Knox County!! Now is an excellent time to scout for these weeds, especially in bean fields. If you would like help with identification call John at 740-397-0401.

If you don’t already have to deal with waterhemp or Palmer amaranth, you don’t want it.  Ask anyone who does.  Neither one of these weeds is easy to manage, and both can cause substantial increases in the cost of herbicide programs, which have to be constantly changed to account for the multiple resistance that will develop over time (not “can”, “will”).  The trend across the country is for Palmer and waterhemp to develop resistance to any new herbicide sites of action that are used in POST treatments within about three cycles of use.  Preventing new infestations of these weeds should be of high priority for Ohio growers.  When not adequately controlled, Palmer amaranth can take over a field faster than any other annual weed we deal with, and waterhemp is a close second.  Taking the time to find and remove any Palmer and waterhemp plants from fields in late-season before they produce seed will go a long way toward maintaining the profitability of Ohio farm operations.  There is information on Palmer amaranth and waterhemp identification on most university websites, including ours –  u.osu.edu/osuweeds/ (go to “weeds” and then “Palmer amaranth”).  An excellent brief video on identification can be found there, along with an ID fact sheet.  The dead giveaway for Palmer amaranth as we move into late summer is the long seedhead, and those on female seed-bearing plants are extremely rough to the touch.  We recommend the following as we progress from now through crop harvest: Continue reading →

Grain Fill Stages in Corn

Source:

Today managing your corn crop requires knowledge of the different growth stages of the corn plant.  Growth stage identification is critical for scouting and proper timing of fertilizer and pesticide applications.  Throughout the growing season I will discuss the various corn growth stages and management issue at each stage. 

Grain Fill Stages

The grain fill period begins with successful pollination and initiation of kernel development, and ends approximately 60 days later when the kernels are physiologically mature.  During grain fill the plant will do all it can to “pump” dry matter into the kernels, sometimes at the expense of the health and maintenance of other plant parts including the roots and lower stalk.

Kernel Development. The embryo and non-embryo sides of each kernel.

Cross-section of primary ears from R1 to R6. The embryo and non-embryo sides of each ear are shown once they are distinguishable.

 

A stress-free grain fill period can maximize the yield potential of a crop, while severe stress during grain fill can cause kernel abortion or lightweight grain and encourage the development of stalk rot (see table 1). The health of the upper leaf canopy is particularly important for achieving maximum grain filling capacity. Some research indicates that the upper leaf canopy, from the ear leaf to the uppermost leaf, is responsible for no less than 60% of the photosynthate necessary for filling the grain.

 

Table 2 shows the average amount of water needed for each growth stage and the cumulative total for the entire growing season.

 

Are Crops Catching Up?

Source: Peter Thomison, Laura Lindsey, OSU Extnesion

Corn –  Crop development varies tremendously across Ohio because of planting dates that range from late April to early July. According to field agronomists in some areas of the state, it looks like late-planted crops are “ rushing through development” …Unlike soybean, corn development is directly related to temperature, i.e. heat unit accumulation. Above average July temperatures (especially nighttime temperatures) have promoted rapid corn growth and development. After corn reaches the V10 stage (and most of our June plantings are near or beyond this stage), leaf collar emergence occurs at approximately one leaf every 50 GDDs.  See Corn Growth & Development posts on this blog for more detailed information on various corn growth stages.

Late planted corn fields (especially those that have adequate soil moisture and good soil fertility and weed control) may appear to be “catching up” with neighboring fields planted earlier. The rapid growth of late planted corn is associated with greater vegetative growth and faster canopy closure, which will help optimize yields. However, it does not mean that the rate of development of later plantings is greater than earlier plantings.  Corn growth and development have distinct meanings (Abendroth et al., 2011). Growth refers to the increase in size of an individual plant (or plant component) whereas development refers to a plant’s progression from earlier to later stages of maturity based on specific criteria (e.g., numbers of leaf collars).  So, while late planted corn may appear to be “catching up in terms” in terms of vegetative growth, i.e. plant height (probably because of longer internodes), it’s not caught up from the standpoint of development (leaf collar stages).

Corn plants can “adjust” their development in response to a shortened growing season. As was noted in a recent C.O.R.N. newsletter article (https://agcrops.osu.edu/newsletter/corn-newsletter/2019-12/will-planting…), a hybrid planted after late May will mature at a faster thermal rate (i.e. require fewer heat units) than the same hybrid planted in late April or early May. One of the consequences of delayed planting is that thermal time (GDD accumulation) from the dent stage (R5) to “black layer” or physiological maturity (R6) is shortened, “though this may simply reflect a premature maturation of the grain caused by the cumulative effects of shorter daylengths and cooler days in early fall or by outright death of the plants by a killing fall freeze” (Nielsen, 2018). Moreover, instead of a grain moisture content of about 30% at black layer, typical for normal planting dates, grain moisture at black layer for late plantings may be as high as 40%, which may require longer field drying and harvest delays.

Soybeans – Continue reading →

Below Normal Rainfall Favored Until at Least Mid-August

Source: Jim Noel, NOAA

The weather pattern is not real supportive of rainfall. The weather models continue to try and support rainfall of normal or slightly above normal, however, current topsoil conditions along with a west to northwest flowing weather pattern does not support that. The last 7 days shows dry conditions across most of the corn and soybean growing areas.

In light of that, we expect 0.25-0.50 inches of rain per week the next two weeks on average with the range from near none to 2 inches in isolated areas. Normal per week about 0.75 inches. Hence, total rainfall for the next two weeks is forecast to average 0.50-1.00 inches with normal being about 1.50 inches for two weeks.

There is some indications that a more normal rainfall pattern will return for the second half of August but still much of Ohio will end August normal or below normal rainfall due to the quite dry first half.

Temperatures for August will average normal to slightly above normal but most maximum temperatures will be 80s to near 90 in the coming week or two.

The latest NOAA/Climate Prediction Center 2-4 week and monthly outlooks can be found at:

https://www.cpc.ncep.noaa.gov/

For the latest on the expanding dry areas in Ohio visit The Drought Monitor at:

https://droughtmonitor.unl.edu/CurrentMap/StateDroughtMonitor.aspx?Midwest

We expect to see the dry areas expand this week across the corn and soybean belt including Ohio.

One Month Outlook Precipitation Probability

One Month Outlook Precipitation Probability

Accumulated Precipitation

Delayed Corn Planting the Disease Risk in Corn

Source: Dr. Pierce Paul, OSU Extension

Disease Risk

In Ohio, several foliar diseases are of greater concern in late-planted corn for a number of reasons, including: 1 – for diseases like gray leaf spot (GLS), northern corn leaf blight (NCLB), and eye spot that are caused by pathogens that overwinter in corn stubble, delayed planting allows more time for inoculum (spores) to buildup, especially in no-till, corn-on-corn fields and 2 – for diseases like common and southern rust that are caused by pathogens that do not overwinter in Ohio, planting late allows more time for spore for blow up from southern states. So, with late planting, not only are more spores likely to be available to infect the crop, they are also more likely to infect the crop at an earlier growth stage and under conditions that are more favorable for disease development. Let us use gray leaf spot as an example. In a “normal” year, although lesions may develop early in the season, this disease typically takes off and spreads after pollination (VT/R1) when the number of spores in the air is high and the weather becomes favorable for infection. Depending on where you are in the state, VT/R1 usually occurs sometime in mid-July. Planting late does not prevent spores from building up or conditions from becoming favorable for the gray leaf spot fungus to infect plant in mid-July, however, the primary difference it that instead of infecting plants at the VT/R1 growth state, the fungus will be infecting plants at a much earlier growth stage, V8-V12, for instance. If the hybrid is susceptible and conditions become favorable, high levels of infection at V8-V12 will result in greater and more rapid diseases development, and consequently, greater damage to the upper leaves before grain-fill is complete. This is also true for NCLB, eye spot, and southern rust.

So, what should I do:

Continue reading →

Expect cornfields pollinating well into August

Source: Dr. Peter Thomison, OSU Extension

According to the National Agricultural Statistics Service for the week ending July 28, 2019, 32% of the state’s corn was silking compared to 75% for the 5-year average. Given the wide range in corn planting dates this year, most corn will not achieve tasselling and silking until we are well into August. The pollination period, the flowering stage in corn, is the most critical period in the development of a corn plant from the standpoint of grain yield determination. Stress conditions (such as hail damage and drought) have the greatest impact on yield potential during the reproductive stage. The following are key steps in the corn pollination process.

Most corn hybrids tassel and silk about the same time although some variability exists among hybrids and environments. On a typical midsummer day, peak pollen shed occurs in the morning between 9:00 and 11:00 a.m. followed by a second round of pollen shed late in the afternoon. Pollen may be shed before the tassel fully emerges. Pollen shed begins in the middle of the central spike of the tassel and spreads out later over the whole tassel with the lower branches last to shed pollen. Pollen grains are borne in anthers, each of which contains a large number of pollen grains. The anthers open and the pollen grains pour out in early to mid morning after dew has dried off the tassels (see figure). Pollen is light and is often carried considerable distances by the wind. However, most of it settles within 20 to 50 feet.

Continue reading →