Near record breaking heat will have an impact on our garden’s vegetables. In general, daytime temperatures that exceed 92°F and nighttime temperatures above 72F will cause problems. The longer the heat lasts, the bigger the impact. Problems include:
Sunscald – Usually a problem with late season heat waves when loss of foliage is more prevalent, but any fruit exposed to direct sunlight can experience bleaching and browning of the exposed parts.
This tomato shows classic sunscald. Photo credit: Flickr
Pollination issues in cucurbits – Heat favors male flower production over female flowers, resulting in fewer fruits, at least temporarily. It may also lead to drop of already set fruit. Bee flights/activity is reduced in hot weather which causes poor pollination and flower drop. In some cases, fruit will be distorted and crooked due to incomplete pollination. Cucumbers are especially sensitive to this disorder.
Tomato/Pepper flower drop – Flowers on these plants have a 48-hour window to pollinate. High temperatures can cause pollen sterility and flower drop. You may not notice the impact until 5 to 6 weeks later when yields are suddenly reduced for a period that aligns with the length of the heat wave.
Sweet corn yields – Although a heat loving crop, daytime temps over 95F can result in poor tip fill, missing kernels, smaller ears, and reduced yield.
Snap bean flower drop – Beans respond by dropping flowers. As soon as temperatures cool down, flowers will develop normally. Unfortunately, this may result in a split set, where some flowers set before the heat and others after. This is a big problem for one-time mechanical harvest but doesn’t have much impact on garden grown beans. Read more Heat and Garden Vegetables
Welcome to this week’s stars: Rudbeckias! Since the first lovely brown-eyed susans have just started blooming here in the Pollinator Garden at the Extension Learning Farm, it’s time for a quick feature on them and a few others of their genus.
First, let’s clear up what they’re not: despite some in the Rudbeckia genus sharing the common name “coneflower”, purple coneflowers are in a different genus – Echinacea. They are not-too-distantly related to Rudbeckias, though, since they fall under the same taxonomic tribe (Heliantheae) within the family Asteraceae. Echinaceas are not native or naturalized* to New York State, but come from warmer, drier areas of the country; though they are popular in gardens and a few might be found in the wild here.
Echinacea purpurea
Plants in the genus Rudbeckia are mostly herbaceous short-lived perennials, with a variety of growth habits and preferred conditions. They are mostly grown for their bright flowers, which make a cheerful addition to just about any garden. All natural varieties have blooms with yellow petals and a darker center, but domestic cultivars can come in different colors – red, for example. If planting one of these, be aware that they may not have the same benefits to pollinators as the regular coloration.
There are three species that are relevant to northern New York.
Rudbeckia hirta
R. triloba
R. laciniata
Let’s start with the common black-eyed susan, R. hirta. It’s native to most of eastern North America, but only considered naturalized* to most of our state, including St. Lawrence County. Despite being one of the most common and popular Rudbeckias, this species is a bit unusual in the genus because it is shorter lived than others, mostly acting as a biennial (two-year life cycle), and puts down a taproot.
Rudbeckia hirta or black-eyed susan
Black-eyed susans can do well in a wide range of soil conditions, and are considered highly drought tolerant. They are also tolerant of juglones, the toxins excreted by walnut-family trees into nearby soil, which can prevent many plants from thriving in those areas. Black-eyed susan was historically used by Native Americans for a variety of internal and external medicinal applications. It is still used by some people in a manner similar to the related Echinacea, and is claimed to stimulate the immune system, though the effectiveness of either plant is widely debated. The part primarily used for these preparations is the root, and the seed heads are considered poisonous even by people promoting the plant’s use.
Brown-eyed susans, R. triloba, also known as three-lobed rudbeckia or thin-leaved coneflower, is next up. This species is labeled ‘Unknown Native Status’ in the New York Flora Atlas, with a note that it is considered native to some parts of the state and naturalized in others. In either case, it’s present in a scattered distribution across much of NYS, including St. Lawrence County. Brown-eyed susans have a more branching growth pattern than the other species here, with the smallest, roundest flower petal shape among the Rudbeckias, and more numerous flowers on each plant as well.
Rudbeckia triloba or brown eyed susan
The one species that is definitively known to be native to our area, as well as most of NYS and the rest of North America, is green-headed coneflower, R. laciniata. Other common names for it include cutleaf coneflower, wild goldenglow, and sochan, derived from its Cherokee name.
Lots of people know milkweed (Asclepias spp.) as the plant that Monarch butterflies need, or recognize its unique seed pods which open to release many silky little parachutes in the fall and early winter – but there’s so much more to this versatile and essential native plant. Let’s explore some important milkweed species, the insects that rely on them, how to eat them as a vegetable, and more!
Out of 70 or so species of the Asclepias genus native to North America, there are about 13 native to New York State; at least three of these are known to be naturally present here in St. Lawrence County. Common milkweed (A. syriaca) is the most prevalent of these, thriving in successional fields, disturbed areas like roadsides, and occasionally in forest clearings.
Common milkweed has coevolved with the monarch butterfly lifecycle. Seen here are the aromatic flowers which feed adults, an egg laid on a leaf, and the caterpillar eating leaves. Caterpillars often travel to a different plant to enter their chrysalis form. Last are the pods and mature seeds with their silk attachments.
Next is swamp milkweed (A. incarnata), in particular the ‘western’ variety (A. incarnata var. incarnata). As the name ‘swamp’ suggests, this species prefers low, wet areas like marshes and swamps, edges of ponds and streams, and poorly-drained parts of fields.
This bumblebee is a generalist making use of swamp milkweed nectar.
Finally, there is forest milkweed or poke milkweed (A. exaltata), which grows mostly in deciduous forests, especially along roads and paths. It’s not as common as the other two in our area, but you might find some.
Photo credit: Pl@ntNet
Some of the species that are native to other parts of NYS might also be found in our area, due to human cultivation. A couple of these include whorled milkweed (A. verticillata) from the Hudson Valley, Catskills, and Greater Niagara regions; and butterfly weed (A. tuberosa), very popular with gardeners for its striking orange blossoms which are unique among milkweeds. Its native range reaches most of the state, but might not normally come as far north as St. Lawrence County.
Whorled milkweed and butterfly weed in the pollinator garden at the Extension Learning Farm
Every species of milkweed provides an essential food source to pollinator populations. They attract all the usual suspects – Bumblebees, Honey bees, other native bees and wasps, and Hummingbirds – as well as supporting lots of butterflies and moths.
The native Asclepias in our area, especially common and swamp milkweed, support 12 species of lepidopterans (butterflies and moths). Milkweed is the sole food source for the larvae of Monarch butterflies (Danaus plexippus), but that’s far from all. The Unexpected Cycnia (Cycnia inopinatus) and Milkweed Tussock Moth or Milkweed Tiger Moth (Euchaetes egle) also exclusively rely on milkweed as a host, and it’s crucial to the Delicate Cycnia or Dogbane Tiger Moth (Cycnia tenera) and Lined Ruby Tiger Moth (Phragmatobia lineata) as one of only two or three host plant genera that they use.
Anyone who has grown or been around milkweed has likely seen some other reddish-orange and black insects that frequent these plants. One is the Milkweed Longhorn (Tetraopes spp.), a type of beetle that has specialized to feed on milkweed plants. Its larvae bore into the roots of the plant to feed and overwinter there, and when the adults emerge in late spring they eat the leaves. There are at least three species in the eastern United States – they are very similar, but vary in their amount of black spotting. Read more Milkweed – Native plant of the Week
