There are at least five yellow-blossoming weeds that welcome spring into the Northeast. They are, in order of appearance, marsh marigold (also called cowslip), buttercup, yellow rocket, dandelion and wild mustard. I’ll apologize to weeds number one and two, ignoring them so as to concentrate on the last three.

Crop Comments: Overheating soil samples – bad ideaA widespread harbinger of spring is yellow rocket. The most common early source of yellow pigment in existing meadows comes from rocket, this year appearing two to three weeks later than normal. In January 2015, Quaker State field crops Extension agents officially designated yellow rocket as “Weed of the Month.” Yellow rocket can be winter-annual or biennial, reproducing from seed which can germinate in both spring and autumn. Young leaves are round or egg-shaped, poised on short stalks. Flowering stems occurring during the second year can, when mature, be at least two feet tall.

Yellow rocket, a member of the mustard family (Brassicaceae), is earliest to flower in that grouping, as the last snow melts. Brassicaceae is a medium-sized and economically important family of flowering plants commonly known as mustards, crucifers or the cabbage family. Rocket’s lower leaves become lobed while stem leaves develop deeper indentations and thick green foliage. Yellow flowers are produced during spring at the upper stem and grouped in clusters. Pod-like fruit is long and sharp at the tip. If not mowed, the fruiting stalk remains all summer.

Yellow rocket forms a taproot but can be removed by hand when small – not an option in meadows. Penn State agronomy agents stress that there are no effective anti-rocket pre-emergence herbicides.

Four years ago, temperatures in Central New York seemed suspended between 45º and 55º for the last 10 days of April. A dairy farmer who had moved up from Pennsylvania a couple years earlier called me, panicked, during the gray of dawn one late April morning. His meadows were infested with yellow flowers, the likes of which he had never seen before. I told him that I was 99% certain that they were yellow rocket, and that mowing them would stall out the stand for the season. As part of a first-cutting hay, baleage or haylage, rocket shouldn’t really cause any problems for cows ingesting it.

My research revealed conditions which made yellow rocket feel very much at home. This plant is a smooth-stemmed native of North America and can be found in new meadows – generally second year growth, along roadsides and in fields. Importantly, soils where this weed is found are low in calcium and very low in phosphorus. This Keystone State transplant dairy farmer was organic, so to rectify this phosphorus shortage (which was documented by soil tests), I recommended he apply some bone meal, since mono-ammonium and di-ammonium phosphates are not allowed by organic standards.

The next yellow-blossoming wild plant heeded as a sign of spring is the dandelion. When grassy to mixed mostly-grass meadows turn from yellow to white fuzz, it’s time to mow these fields. Occasionally remove the grayish-white fuzzy mat from the haybine, then throw it into the swath to be chopped or round-baled, since its feed value is generous.

The last yellow bloomer to announce spring is wild mustard. Wild mustard tries to take over new seedings as well as spring-planted small grain stands, but not till the last week of May – or likely the first week of June this year, due to pokey onset of spring. Both yellow rocket and wild mustard are members of the Brassicaceae family, making them second cousins.

Wild mustard boasts the following first cousins: tame yellow mustard, all the cabbages, Brussels sprouts, broccoli, cauliflower, kale, kohlrabi, canola, collards, turnips and rutabaga. Wild mustard can be smooth stemmed – confused somewhat with yellow rocket.

But wild mustard petal pigment leans toward pastel yellow. Rocket’s petals sport just a tinge of green. A small taste of leaves of each smooth specimen reveals that rocket is somewhat bitter – though not toxic – and wild mustard is a little radishy. Rocket matures before mustard, but rocket seeds are somewhat smaller than those of their second cousin maturing later.

Yellow rocket has no problem with soils in the 45º – 50º range in an established hay stand, while yellow mustard in an adjacent oat/alfalfa seeding wants its topsoil to be five to 10 degrees warmer to encourage germination. Odds are that if rocket is much more prevalent than mustard on neighboring fields, other nearby parcels are likely too cold for corn to germinate enthusiastically.

Last week’s column touched on the non-wisdom of rushing corn planting. Now I’ll discuss the non-wisdom of rushing soil sample drying. About a half century ago, during my career as a dairy and agronomy Extension agent, a home gardener brought a soil sample to the office to have me perform a simple pH test, to see if his plot needed any lime. I couldn’t believe the result and repeated the test. The tiny slurry of mud and bromothymol blue displayed dark blue-green color, off the charts, making me guess at a pH of 8.2. I asked the man if he’d heavily limed the piece; he said no. How about wood ashes? Again, no. How did he dry the sample? He helped the drying process, using a 250º oven for 20 minutes.

I told him that was likely the reason for the super high pH, but that I would back up my assessment by contacting a full-time agronomist, Cornell professor W. Shaw Reid. Professor Reid said that the extra high drying temperature dislodged the cations (positively charged atomic particles) on the soil granules’ microscopic surfaces. Those cations include calcium, magnesium, potassium, zinc and sodium (and other lesser elements). Those cations displaced hydrogen cations.

Here’s where the train derailed. Explained as simply as possibly, pH is the negative logarithm of the hydrogen ion concentration. Lowering hydrogen ions naturally or artificially, like with the baking gardener, raised the pH.